The fact of this problem is the engine of the game crashing you. Not the game itself.
Try this:
Go to the settings in steam
Then go to the in-game tab
Tick off the enable steam community ingame (WARNING: This will disable the function of you speaking with your friends in the game, unless you alt+tab or you play in windowed mode)
Play a couple of days with those settings
Tick that setting on again
Now it should work.
The exact same problem happened to me in HL2 DM, but it worked with that thing I showed. :P