diff --git a/include/osg/Texture b/include/osg/Texture
index 8166b6303..50399629d 100644
--- a/include/osg/Texture
+++ b/include/osg/Texture
@@ -647,6 +647,9 @@ class SG_EXPORT Texture : public osg::StateAttribute
             
             TextureObjectListMap    _textureObjectListMap;
             
+            // mutex to keep access serialized.
+            OpenThreads::Mutex      _mutex;
+            
         };
         
         
diff --git a/src/osg/Drawable.cpp b/src/osg/Drawable.cpp
index b8e082b2c..c7a35fec4 100644
--- a/src/osg/Drawable.cpp
+++ b/src/osg/Drawable.cpp
@@ -33,13 +33,17 @@ using namespace osg;
 // is set.  Used osg::Drawable::deleteDisplayList(..) and flushDeletedDisplayLists(..) below.
 typedef std::list<GLuint> DisplayListList;
 typedef std::map<GLuint,DisplayListList> DeletedDisplayListCache;
+
+static OpenThreads::Mutex s_mutex_deletedDisplayListCache;
 static DeletedDisplayListCache s_deletedDisplayListCache;
-static DeletedDisplayListCache s_deletedVertexBufferObjectCache;
 
 void Drawable::deleteDisplayList(unsigned int contextID,GLuint globj)
 {
     if (globj!=0)
     {
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedDisplayListCache);
+#endif
         // insert the globj into the cache for the appropriate context.
         s_deletedDisplayListCache[contextID].push_back(globj);
     }
@@ -58,31 +62,45 @@ void Drawable::flushDeletedDisplayLists(unsigned int contextID,double /*currentT
 
     unsigned int noDeleted = 0;
 
-    DeletedDisplayListCache::iterator citr = s_deletedDisplayListCache.find(contextID);
-    if (citr!=s_deletedDisplayListCache.end())
     {
-        DisplayListList& dll = citr->second;
-       
-        for(DisplayListList::iterator ditr=dll.begin();
-            ditr!=dll.end() && elapsedTime<availableTime;
-            )
-        {
-            glDeleteLists(*ditr,1);
-            ditr = dll.erase(ditr);
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
-           ++noDeleted;
-         }
-    }
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedDisplayListCache);
+#endif
 
+        DeletedDisplayListCache::iterator citr = s_deletedDisplayListCache.find(contextID);
+        if (citr!=s_deletedDisplayListCache.end())
+        {
+            DisplayListList& dll = citr->second;
+
+            for(DisplayListList::iterator ditr=dll.begin();
+                ditr!=dll.end() && elapsedTime<availableTime;
+                )
+            {
+                glDeleteLists(*ditr,1);
+                ditr = dll.erase(ditr);
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+               ++noDeleted;
+             }
+        }
+    }
+    
     if (noDeleted!=0) notify(INFO)<<"Number display lists deleted = "<<noDeleted<<std::endl;
 
     availableTime -= elapsedTime;
 }
 
+
+static OpenThreads::Mutex s_mutex_deletedVertexBufferObjectCache;
+static DeletedDisplayListCache s_deletedVertexBufferObjectCache;
+
 void Drawable::deleteVertexBufferObject(unsigned int contextID,GLuint globj)
 {
     if (globj!=0)
     {
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedVertexBufferObjectCache);
+#endif
+        
         // insert the globj into the cache for the appropriate context.
         s_deletedVertexBufferObjectCache[contextID].push_back(globj);
     }
@@ -100,28 +118,33 @@ void Drawable::flushDeletedVertexBufferObjects(unsigned int contextID,double /*c
     double elapsedTime = 0.0;
 
 
-    DeletedDisplayListCache::iterator citr = s_deletedVertexBufferObjectCache.find(contextID);
-    if (citr!=s_deletedVertexBufferObjectCache.end())
     {
-        const Extensions* extensions = getExtensions(contextID,true);
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedVertexBufferObjectCache);
+#endif
 
-        unsigned int noDeleted = 0;
-
-        DisplayListList& dll = citr->second;
-       
-        for(DisplayListList::iterator ditr=dll.begin();
-            ditr!=dll.end() && elapsedTime<availableTime;
-            )
+        DeletedDisplayListCache::iterator citr = s_deletedVertexBufferObjectCache.find(contextID);
+        if (citr!=s_deletedVertexBufferObjectCache.end())
         {
-            extensions->glDeleteBuffers(1,&(*ditr));
-            ditr = dll.erase(ditr);
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
-            ++noDeleted;
-        }
+            const Extensions* extensions = getExtensions(contextID,true);
 
-        if (noDeleted!=0) notify(osg::INFO)<<"Number VBOs deleted = "<<noDeleted<<std::endl;
-    }
-    
+            unsigned int noDeleted = 0;
+
+            DisplayListList& dll = citr->second;
+
+            for(DisplayListList::iterator ditr=dll.begin();
+                ditr!=dll.end() && elapsedTime<availableTime;
+                )
+            {
+                extensions->glDeleteBuffers(1,&(*ditr));
+                ditr = dll.erase(ditr);
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+                ++noDeleted;
+            }
+
+            if (noDeleted!=0) notify(osg::INFO)<<"Number VBOs deleted = "<<noDeleted<<std::endl;
+        }
+    }    
     
     availableTime -= elapsedTime;
 }
diff --git a/src/osg/FragmentProgram.cpp b/src/osg/FragmentProgram.cpp
index cd61704a8..34c404b4d 100644
--- a/src/osg/FragmentProgram.cpp
+++ b/src/osg/FragmentProgram.cpp
@@ -25,12 +25,18 @@ using namespace osg;
 // is set.
 typedef std::list<GLuint> FragmentProgramObjectList;
 typedef std::map<unsigned int,FragmentProgramObjectList> DeletedFragmentProgramObjectCache;
+
+static OpenThreads::Mutex                s_mutex_deletedFragmentProgramObjectCache;
 static DeletedFragmentProgramObjectCache s_deletedFragmentProgramObjectCache;
 
 void FragmentProgram::deleteFragmentProgramObject(unsigned int contextID,GLuint handle)
 {
     if (handle!=0)
     {
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedFragmentProgramObjectCache);
+#endif
+
         // insert the handle into the cache for the appropriate context.
         s_deletedFragmentProgramObjectCache[contextID].push_back(handle);
     }
@@ -46,24 +52,29 @@ void FragmentProgram::flushDeletedFragmentProgramObjects(unsigned int contextID,
     osg::Timer_t start_tick = timer.tick();
     double elapsedTime = 0.0;
 
-    DeletedFragmentProgramObjectCache::iterator citr = s_deletedFragmentProgramObjectCache.find(contextID);
-    if (citr!=s_deletedFragmentProgramObjectCache.end())
     {
-    
-        const Extensions* extensions = getExtensions(contextID,true);
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedFragmentProgramObjectCache);
+#endif
 
-        FragmentProgramObjectList& vpol = citr->second;
-    
-        for(FragmentProgramObjectList::iterator titr=vpol.begin();
-            titr!=vpol.end() && elapsedTime<availableTime;
-            )
+        DeletedFragmentProgramObjectCache::iterator citr = s_deletedFragmentProgramObjectCache.find(contextID);
+        if (citr!=s_deletedFragmentProgramObjectCache.end())
         {
-            extensions->glDeletePrograms( 1L, &(*titr ) );
-            titr = vpol.erase(titr);
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
+            const Extensions* extensions = getExtensions(contextID,true);
+
+            FragmentProgramObjectList& vpol = citr->second;
+
+            for(FragmentProgramObjectList::iterator titr=vpol.begin();
+                titr!=vpol.end() && elapsedTime<availableTime;
+                )
+            {
+                extensions->glDeletePrograms( 1L, &(*titr ) );
+                titr = vpol.erase(titr);
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+            }
         }
     }
-    
+        
     availableTime -= elapsedTime;
 }
 
diff --git a/src/osg/Texture.cpp b/src/osg/Texture.cpp
index cffa3e574..dfa5b58bb 100644
--- a/src/osg/Texture.cpp
+++ b/src/osg/Texture.cpp
@@ -70,6 +70,10 @@ Texture::TextureObject* Texture::TextureObjectManager::reuseTextureObject(unsign
                                                                              GLsizei   depth,
                                                                              GLint     border)
 {
+#ifdef THREAD_SAFE_DELETE_LISTS
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+#endif
+
     TextureObjectList& tol = _textureObjectListMap[contextID];
     for(TextureObjectList::iterator itr = tol.begin();
         itr != tol.end();
@@ -94,6 +98,10 @@ Texture::TextureObject* Texture::TextureObjectManager::reuseTextureObject(unsign
 
 void Texture::TextureObjectManager::addTextureObjects(Texture::TextureObjectListMap& toblm)
 {
+#ifdef THREAD_SAFE_DELETE_LISTS
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+#endif
+
     for(TextureObjectListMap::iterator itr = toblm.begin();
         itr != toblm.end();
         ++itr)
@@ -105,6 +113,8 @@ void Texture::TextureObjectManager::addTextureObjects(Texture::TextureObjectList
 
 void Texture::TextureObjectManager::addTextureObjectsFrom(Texture& texture)
 {
+    OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+
     texture.takeTextureObjects(_textureObjectListMap);
 }
 
@@ -113,47 +123,54 @@ void Texture::TextureObjectManager::flushTextureObjects(unsigned int contextID,d
     // if no time available don't try to flush objects.
     if (availableTime<=0.0) return;
 
+
     const osg::Timer& timer = *osg::Timer::instance();
     osg::Timer_t start_tick = timer.tick();
     double elapsedTime = 0.0;
-    
-    TextureObjectListMap::iterator tmitr = _textureObjectListMap.find(contextID);
-    if (tmitr!=_textureObjectListMap.end())
-    {
-        TextureObjectList& tol = tmitr->second;
 
-        // reset the time of any uninitialized objects.
-        TextureObjectList::iterator itr;
-        for(itr=tol.begin();
-            itr!=tol.end();
-            ++itr)
+    {    
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(_mutex);
+#endif
+
+        TextureObjectListMap::iterator tmitr = _textureObjectListMap.find(contextID);
+        if (tmitr!=_textureObjectListMap.end())
         {
-            if ((*itr)->_timeStamp==0.0) (*itr)->_timeStamp=currentTime;
-        }
+            TextureObjectList& tol = tmitr->second;
 
-        double expiryTime = currentTime-_expiryDelay;
-
-        unsigned int numTexturesDeleted = 0;
-        for(itr=tol.begin();
-            itr!=tol.end() && elapsedTime<availableTime;
-            )
-        {
-            if ((*itr)->_timeStamp<expiryTime)
+            // reset the time of any uninitialized objects.
+            TextureObjectList::iterator itr;
+            for(itr=tol.begin();
+                itr!=tol.end();
+                ++itr)
             {
-                glDeleteTextures( 1L, &((*itr)->_id));
-                itr = tol.erase(itr);
-                ++numTexturesDeleted;
+                if ((*itr)->_timeStamp==0.0) (*itr)->_timeStamp=currentTime;
             }
-            else
-            {
-                ++itr;
-            }
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
-        }
 
-        if (numTexturesDeleted) notify(osg::INFO)<<"Number of Texture's deleted = "<<numTexturesDeleted<<std::endl;
+            double expiryTime = currentTime-_expiryDelay;
+
+            unsigned int numTexturesDeleted = 0;
+            for(itr=tol.begin();
+                itr!=tol.end() && elapsedTime<availableTime;
+                )
+            {
+                if ((*itr)->_timeStamp<expiryTime)
+                {
+                    glDeleteTextures( 1L, &((*itr)->_id));
+                    itr = tol.erase(itr);
+                    ++numTexturesDeleted;
+                }
+                else
+                {
+                    ++itr;
+                }
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+            }
+
+            if (numTexturesDeleted) notify(osg::INFO)<<"Number of Texture's deleted = "<<numTexturesDeleted<<std::endl;
+        }
     }
-    
+        
     availableTime -= elapsedTime;
 }
 
diff --git a/src/osg/VertexProgram.cpp b/src/osg/VertexProgram.cpp
index 8a45e308a..3149bef4a 100644
--- a/src/osg/VertexProgram.cpp
+++ b/src/osg/VertexProgram.cpp
@@ -25,12 +25,18 @@ using namespace osg;
 // is set.
 typedef std::list<GLuint> VertexProgramObjectList;
 typedef std::map<unsigned int,VertexProgramObjectList> DeletedVertexProgramObjectCache;
+
+static OpenThreads::Mutex              s_mutex_deletedVertexProgramObjectCache;
 static DeletedVertexProgramObjectCache s_deletedVertexProgramObjectCache;
 
 void VertexProgram::deleteVertexProgramObject(unsigned int contextID,GLuint handle)
 {
     if (handle!=0)
     {
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedVertexProgramObjectCache);
+#endif
+
         // insert the handle into the cache for the appropriate context.
         s_deletedVertexProgramObjectCache[contextID].push_back(handle);
     }
@@ -46,24 +52,30 @@ void VertexProgram::flushDeletedVertexProgramObjects(unsigned int contextID,doub
     osg::Timer_t start_tick = timer.tick();
     double elapsedTime = 0.0;
 
-    DeletedVertexProgramObjectCache::iterator citr = s_deletedVertexProgramObjectCache.find(contextID);
-    if (citr!=s_deletedVertexProgramObjectCache.end())
     {
-    
-        const Extensions* extensions = getExtensions(contextID,true);
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedVertexProgramObjectCache);
+#endif
 
-        VertexProgramObjectList& vpol = citr->second;
-    
-        for(VertexProgramObjectList::iterator titr=vpol.begin();
-            titr!=vpol.end() && elapsedTime<availableTime;
-            )
+        DeletedVertexProgramObjectCache::iterator citr = s_deletedVertexProgramObjectCache.find(contextID);
+        if (citr!=s_deletedVertexProgramObjectCache.end())
         {
-            extensions->glDeletePrograms( 1L, &(*titr ) );
-            titr = vpol.erase(titr);
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
+
+            const Extensions* extensions = getExtensions(contextID,true);
+
+            VertexProgramObjectList& vpol = citr->second;
+
+            for(VertexProgramObjectList::iterator titr=vpol.begin();
+                titr!=vpol.end() && elapsedTime<availableTime;
+                )
+            {
+                extensions->glDeletePrograms( 1L, &(*titr ) );
+                titr = vpol.erase(titr);
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+            }
         }
     }
-    
+        
     availableTime -= elapsedTime;
 }
 
diff --git a/src/osgDB/DatabasePager.cpp b/src/osgDB/DatabasePager.cpp
index ef7dc31f9..656aac028 100644
--- a/src/osgDB/DatabasePager.cpp
+++ b/src/osgDB/DatabasePager.cpp
@@ -28,8 +28,8 @@ DatabasePager::DatabasePager()
     _threadPriorityDuringFrame = PRIORITY_MIN;
     _threadPriorityOutwithFrame = PRIORITY_MIN;
 
-    _changeAutoUnRef = false;
-    _valueAutoUnRef = false;
+    _changeAutoUnRef = true;
+    _valueAutoUnRef = true;
     _changeAnisotropy = false;
     _valueAnisotropy = 1.0f;
 
diff --git a/src/osgGL2/ProgramObject.cpp b/src/osgGL2/ProgramObject.cpp
index c8971b1a1..129c5d412 100644
--- a/src/osgGL2/ProgramObject.cpp
+++ b/src/osgGL2/ProgramObject.cpp
@@ -75,12 +75,17 @@ private:
 
 typedef std::list<GLhandleARB> GL2ObjectList;
 typedef std::map<unsigned int, GL2ObjectList> DeletedGL2ObjectCache;
+
+static OpenThreads::Mutex    s_mutex_deletedGL2ObjectCache;
 static DeletedGL2ObjectCache s_deletedGL2ObjectCache;
 
 void ProgramObject::deleteObject(unsigned int contextID, GLhandleARB handle)
 {
     if (handle!=0)
     {
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedGL2ObjectCache);
+#endif
         // add handle to the cache for the appropriate context.
         s_deletedGL2ObjectCache[contextID].push_back(handle);
     }
@@ -95,30 +100,36 @@ void ProgramObject::flushDeletedGL2Objects(unsigned int contextID,double /*curre
     osg::Timer_t start_tick = timer.tick();
     double elapsedTime = 0.0;
 
-    DeletedGL2ObjectCache::iterator citr = s_deletedGL2ObjectCache.find(contextID);
-    if( citr != s_deletedGL2ObjectCache.end() )
     {
-        const Extensions* extensions = Extensions::Get(contextID,true);
+#ifdef THREAD_SAFE_DELETE_LISTS
+        OpenThreads::ScopedLock<OpenThreads::Mutex> lock(s_mutex_deletedGL2ObjectCache);
+#endif
 
-	if (!extensions->isGlslSupported())
-	{
-	    // can we really get here?
-	    osg::notify(osg::WARN) << "flushDeletedGL2Objects not supported by OpenGL driver" << std::endl;
-	    return;
-	}
-
-        GL2ObjectList& vpObjectList = citr->second;
-
-        for(GL2ObjectList::iterator titr=vpObjectList.begin();
-            titr!=vpObjectList.end() && elapsedTime<availableTime;
-            )
+        DeletedGL2ObjectCache::iterator citr = s_deletedGL2ObjectCache.find(contextID);
+        if( citr != s_deletedGL2ObjectCache.end() )
         {
-            extensions->glDeleteObject( *titr );
-            titr = vpObjectList.erase( titr );
-            elapsedTime = timer.delta_s(start_tick,timer.tick());
+            const Extensions* extensions = Extensions::Get(contextID,true);
+
+	    if (!extensions->isGlslSupported())
+	    {
+	        // can we really get here?
+	        osg::notify(osg::WARN) << "flushDeletedGL2Objects not supported by OpenGL driver" << std::endl;
+	        return;
+	    }
+
+            GL2ObjectList& vpObjectList = citr->second;
+
+            for(GL2ObjectList::iterator titr=vpObjectList.begin();
+                titr!=vpObjectList.end() && elapsedTime<availableTime;
+                )
+            {
+                extensions->glDeleteObject( *titr );
+                titr = vpObjectList.erase( titr );
+                elapsedTime = timer.delta_s(start_tick,timer.tick());
+            }
         }
     }
-    
+        
     availableTime -= elapsedTime;
 }