Hi,
When you say your game crashes, do you mean it crashes and dumps you out to the desktop, or does it lockup in game and freeze?
any other information before it crashes? like no .dll or lost connection, or somthing dump?
Can you play Ins in single player mode, by creating a game. create battle and play in there.
Windows XP or Vista?
Papertarget might be right somtimes you have to go through the pain of unstalling and reinstalling steam...