Since this also seems to have occurred after the most recent kernel update, I'm almost certain it has something to do with the update. I'm running Ubuntu Lucid Lynx on a 64-bit system, kernel 2.6.32-24 generic, and I'm having the same problem, but with Half-Life 1 and Counter Strike, which are both Goldsource games. Please see my post in "Steam Games Unable to Play" also in this forum. I would like to find out how to fix this, as Half-Life is the only game I really play on my PC...
