diff -r 0ff03867bdb6 -r 39b39e1a406e userlibandfileserver/fileserver/sfile/sf_thread.cpp
--- a/userlibandfileserver/fileserver/sfile/sf_thread.cpp	Wed Jul 21 14:46:58 2010 +0100
+++ b/userlibandfileserver/fileserver/sfile/sf_thread.cpp	Thu Jul 22 16:46:39 2010 +0100
@@ -834,10 +834,9 @@
 //
 	{
 	__ASSERT_ALWAYS(FsThreadManager::IsDriveThread(iDriveNumber,EFalse),Fault(EDriveThreadNotifyUser1));
-	// NB For read-ahead or a flush-dirty write request generated by the file cache, the session will be NULL: 
+	// NB For read-ahead or a flush-dirty write request generated by the file cache, the request or the session may be NULL: 
 	// in this case assume that notify user is set (as it's the safest option)
-	CSessionFs* session = iRequest->Session();
-	return session ?  session->GetNotifyUser() : ETrue;
+	return iRequest && iRequest->Session() ?  iRequest->Session()->GetNotifyUser() : ETrue;
 	}
 
 void CDriveThread::StartFinalisationTimer()
@@ -926,24 +925,34 @@
 	}
 
 
-CPluginThread::CPluginThread(CFsPlugin& aPlugin)
-  : iPlugin(aPlugin)
+CPluginThread::CPluginThread(CFsPlugin& aPlugin, RLibrary aLibrary)
+  : iPlugin(aPlugin), iLib(aLibrary)
 	{
 	/** @prototype */
 	iOperationLock.Close();
 	iPlugin.Open();
+	
+    /* 
+    Duplicate the handle to the DLL which created the plugin to prevent 
+    TFsRemovePlugin::DoRequestL() from unmapping the DLL's code segment before
+    this thread's destructor has been called as the destructor closes the plugin 
+    which results in a call to the plugin's derived destructor contained in the DLL (!)
+    */ 
+    TInt r = iLib.Duplicate(iThread, EOwnerProcess);
+    __ASSERT_ALWAYS(r==KErrNone, Fault(EFsThreadConstructor));
 	}
 
 CPluginThread::~CPluginThread()
     {
     iPlugin.Close();
+	iLib.Close();
     }
 
 
-CPluginThread* CPluginThread::NewL(CFsPlugin& aPlugin)
+CPluginThread* CPluginThread::NewL(CFsPlugin& aPlugin, RLibrary aLibrary)
 	{
 	__PRINT(_L("CPluginThread::NewL()"));
-	CPluginThread* pT=new(ELeave) CPluginThread(aPlugin);
+	CPluginThread* pT=new(ELeave) CPluginThread(aPlugin, aLibrary);
 	TInt r=pT->Initialise();
 
 	/** @prototype */