diff --git a/include/osgDB/DatabasePager b/include/osgDB/DatabasePager
index d6eb751ad..099de9f0a 100644
--- a/include/osgDB/DatabasePager
+++ b/include/osgDB/DatabasePager
@@ -350,6 +350,7 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         {
             DatabaseRequest():
                 osg::Referenced(true),
+                _valid(false),
                 _frameNumberFirstRequest(0),
                 _timestampFirstRequest(0.0),
                 _priorityFirstRequest(0.f),
@@ -359,7 +360,12 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
                 _numOfRequests(0),
                 _requestQueue(0)
             {}
-            
+
+            void invalidate();
+
+            bool valid() const { return _valid; }
+
+            bool                                _valid;
             std::string                         _fileName;
             int                                 _frameNumberFirstRequest;
             double                              _timestampFirstRequest;
@@ -371,7 +377,7 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
             osg::observer_ptr<osg::Group>       _groupForAddingLoadedSubgraph;
             osg::ref_ptr<osg::Node>             _loadedModel;
             DataToCompileMap                    _dataToCompileMap;
-            osg::ref_ptr<Options> _loadOptions;
+            osg::ref_ptr<Options>               _loadOptions;
             RequestQueue*                       _requestQueue;
 
             bool isRequestCurrent (int frameNumber) const
@@ -382,12 +388,16 @@ class OSGDB_EXPORT DatabasePager : public osg::NodeVisitor::DatabaseRequestHandl
         
         struct RequestQueue : public osg::Referenced
         {
+        public:
             typedef std::vector< osg::ref_ptr<DatabaseRequest> > RequestList;
 
             void sort();
-                                    
+
             RequestList         _requestList;
             OpenThreads::Mutex  _requestMutex;
+
+        protected:
+            virtual ~RequestQueue();
         };
 
         
diff --git a/src/osgDB/DatabasePager.cpp b/src/osgDB/DatabasePager.cpp
index 28da47b74..89362a785 100644
--- a/src/osgDB/DatabasePager.cpp
+++ b/src/osgDB/DatabasePager.cpp
@@ -279,8 +279,30 @@ struct DatabasePager::SortFileRequestFunctor
 
 /////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 //
-//  ReadQueue
+//  RequestQueue
 //
+void DatabasePager::DatabaseRequest::invalidate()
+{
+    osg::notify(osg::INFO)<<"   DatabasePager::DatabaseRequest::invalidate()."<<std::endl;
+    _valid = false;
+    _groupForAddingLoadedSubgraph = 0;
+    _loadedModel = 0;
+    _dataToCompileMap.clear();
+    _requestQueue = 0;
+    _requestQueue = 0;
+}
+
+DatabasePager::RequestQueue::~RequestQueue()
+{
+    osg::notify(osg::INFO)<<"DatabasePager::RequestQueue::~RequestQueue() Destructing queue."<<std::endl;
+    for(RequestList::iterator itr = _requestList.begin();
+        itr != _requestList.end();
+        ++itr)
+    {
+        (*itr)->invalidate();
+    }
+}
+
 void DatabasePager::RequestQueue::sort()
 {
     std::sort(_requestList.begin(),_requestList.end(),SortFileRequestFunctor());
@@ -1295,6 +1317,12 @@ void DatabasePager::requestNodeFile(const std::string& fileName,osg::Group* grou
     if (databaseRequestRef.valid())
     {
         DatabaseRequest* databaseRequest = dynamic_cast<DatabaseRequest*>(databaseRequestRef.get());
+        if (databaseRequest && databaseRequest->valid())
+        {
+            osg::notify(osg::NOTICE)<<"DatabaseRequest has been previously invalidated whilst still attached to scene graph."<<std::endl;
+            databaseRequest = 0;
+        }
+
         if (databaseRequest)
         {
             osg::notify(osg::INFO)<<"DatabasePager::requestNodeFile("<<fileName<<") updating already assigned."<<std::endl;