If you're using wine 1.2 or earlier, this may be fixed with wine 1.3, as a steam update caused many source games to crash around August 19, 2010 in 1.2 and earlier versions of wine. If not, I'm pretty sure your problem is related to GameOverlayRenderer.dll, which is found in .wine/drive c/Program Files/Steam. All you have to do is go to winecfg-->libraries tab and in the box type "gameoverlayrenderer.dll, "Add" then "Edit" then select "Disable." Let us know which one of these, if either, works for you.
