Yeah, for me C2 crashes occasionally while using it, and without fail whenever I have been using Photoshop at the same time and close C2 it will definitely crash.
I am running latest version of C2 on Win8 Pro machine, and if C2 crashes, when I shut down the OS it hangs for a bit then brings up a message about a 'Place Holder Window' still being open and gives the option to force the shut down or go back and close the 'Place Holder' window. (This 'Place Holder' window thing only comes up when I have been using C2, and I have been using Win8 and Photoshop since the consumer preview.)
Anyway if I opt to go and close the window - there is no 'Place Holder' window to be found - and Task Manager shows nothing running.
I have had this problem since I came on board (Dec 2012), but C2 is such a cool tool I just expect it and work around it. I have been looking out for specific things that cause it but it pretty random - except when using graphics intensive software at the same time.
My guess is it is graphics related, since it always happens when using Photoshop, but randomly if I'm not....