I run VMware fusion on my Mac to develop and test Windows applications. I've noticed when running XP as the guest OS it will sometimes hang with a black screen when I resume it (I think it happens when an automatic update for XP has occurred).
Anyway, I couldn't get it to respond and attempting to close it didn't work. I could suspend it, but it just saves the bad state. Finally I found the answer at VMware Communities: http://communities.vmware.com/message/893646#893646