Index: /trunk/src/VBox/VMM/PDMQueue.cpp
===================================================================
--- /trunk/src/VBox/VMM/PDMQueue.cpp	(revision 19785)
+++ /trunk/src/VBox/VMM/PDMQueue.cpp	(revision 19786)
@@ -652,6 +652,9 @@
     RTR0PTR           pItemsR0 = ASMAtomicXchgR0Ptr(&pQueue->pPendingR0, NIL_RTR0PTR);
 
-    AssertMsg(pItems || pItemsRC || pItemsR0, ("ERROR: can't all be NULL now!\n"));
-
+    if (    !pItems 
+        &&  !pItemsRC
+        &&  !pItemsR0)
+        /* Somebody was racing us. */
+        return true;
 
     /*