diff -r 3aa07f06a4b7 -r 31d52bbe209c windowing/windowserver/nga/SERVER/scrdev.cpp
--- a/windowing/windowserver/nga/SERVER/scrdev.cpp	Tue Apr 20 16:38:10 2010 +0100
+++ b/windowing/windowserver/nga/SERVER/scrdev.cpp	Fri Apr 23 14:57:14 2010 +0100
@@ -46,6 +46,7 @@
 		,iClientScreenDevicePointer(aClientScreenDevicePointer)
 	{
 	MWsScreen* pOI=Screen();
+	WS_ASSERT_ALWAYS(pOI, EWsPanicNoScreen);
 	iDispCont=pOI->ObjectInterface<MWsDisplayControl>();
 	iDispMap =pOI->ObjectInterface<MWsDisplayMapping>();
 	iTestScreenCapture = pOI->ObjectInterface<MWsTestScreenCapture>();