Seems 10.4s+ break openGL so you cannot play some old games in steam (and maybe not in steam). re: http://forums.steampowered.com/forums/showthread.php?t=1288578 Essentially you have to do this:- Anyone still receiving this problem it is due to the new 3.3/4.0 OpenGL files. Download this and place it in your GameData folder. http://www.filefront.com/16696483/atioglxx.rar Same thing works for Jedi Outcast and Return to Castle Wolfenstein. Rumor is that the new 10.6 will fix this issue with a updated OpenGL but the latest leaked versions still seem to have this issue. When the 10.6 drivers do come out, try to move this file out of the folder to see if the problem is fixed or not so you are always running the latest It wasn't fixed in 10.6 btw, so anyone know if this will be fixed in 10.7?