Index: /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-win.cpp
===================================================================
--- /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-win.cpp	(revision 78163)
+++ /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc-win.cpp	(revision 78164)
@@ -560,4 +560,9 @@
 static int vboxClipboardSyncInternal(PVBOXCLIPBOARDCONTEXT pCtx)
 {
+    AssertPtrReturn(pCtx, VERR_INVALID_POINTER);
+
+    if (pCtx->pClient == NULL) /* If we don't have any client data (yet), bail out. */
+        return VINF_SUCCESS;
+
     uint32_t uFormats;
     int rc = VBoxClipboardWinGetFormats(&pCtx->Win, &uFormats);
Index: /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp
===================================================================
--- /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp	(revision 78163)
+++ /trunk/src/VBox/HostServices/SharedClipboard/VBoxSharedClipboardSvc.cpp	(revision 78164)
@@ -246,4 +246,6 @@
 void vboxSvcClipboardReportMsg (VBOXCLIPBOARDCLIENTDATA *pClient, uint32_t u32Msg, uint32_t u32Formats)
 {
+    AssertPtrReturnVoid(pClient);
+
     if (VBoxSvcClipboardLock())
     {