Have a client with an intermittent problem.
At random times, and for no particular reason associated with activity at the time, IE will start up, display a white screen with no tool, tile, menu or status bars. Ctrl/Alt/Del to stop process is the only way to go anywhere.
Scanned for virus (with avast!) spy-ware (with SpyWareDoctor) ad-ware (with ad-aware 2007) - none found.
Cannot "reproduce" the problem as it seems to have a life (and mind) of its own.