Is it anything like the problem I've been having
So far I've only had starcraft crash on me when I'm playing multiplayer over LAN (UDP) and I haven't been able to remedy the problem.
Mind you, my issue doesn't happen every game...I can successfully play a full hour-long LAN game at times, but some games I play for about 5 minutes and my whole system seizes up.
It seems like a similar behaviour to your problem...Programs running in the background continue to function but I'm unable to exit starcraft in any way (Alt+tab, Ctrl+alt+del, etc...) except a hard reset.
EDIT: I'm running SC with multiple compatibility options because of a common issue with the colors and Windows Vista/7.
Still having the same system crashes.