wine users - Jul 2009 - TF2 random quit

Hello all. I'm having a spot of trouble with Team Fortress 2 under WINE. You
see, the game appears to randomly stop working and blank out. Here are my system
specs:

Motherboard: MSI 790GX-G65
RAM: 4GB DDR3
CPU: AMD Phenom II
Video Card:PNY/Nvidia GTS250 Performance Edition

After the screen blacks out, I am returned to my desktop, with the resolution
still at TF2's max. (Not as big as Nvidia Xserver's max.) But that's
not the big problem. How do I stop TF2 from randomly quitting?

Shoot. Darn thing doesn't let me edit. Oh well.

I should add that I'm running the latest Ubuntu 9.04 (as of July 12, 2:12 AM
Eastern Time).