I can only redirect you to geever's post right above yours. Without more information, there's not much we can do.
Geever's instructions are:
1. try running the game from command line
2. open the console (Sh+ESC) and write 'setdeveloper DEBUG_CLIENT' (+enter) in.
3. Start a campaign, reproduce the crash.
Fair enough, but I could use a bit of help on the directions. I think I understand # 1, but I don't see the point? #2 and #3 are clear, but what is supposed to happen after I reproduce the crash? Do I get something in the console, a log file, or something else? Can you tell me what I'm looking for?
Thanks,
Ken