Yeah, mine reboots while playing Battlefield 2 for a while. It's really annoying. Opening the PC case did stabilize it a lot but it still crashes from time to time. The CPU temperature is an average of 10 degrees lower with an open case (50° when idle, around 60° when playing, instead of 70° when playing with a closed case [ = crash ]).

Funny thing is, my two Mozilla programs (Firefox and Thunderbirds) crash a lot more with a closed case, though I doubt they really need much of the CPU. :-k

hmm...i think i had that same problem, but my pc didn't restart, it just crashed onto the desktop and i had to shut it down, it looked like it zoomed in at the top right of the screen, i couldn't see the start menu or anything..but..i have windows me, so you can't have that . I went into quake and right away, it crashed, i think my graphics card was over heated, its old..so.., i solved that problem by tweaking the q3 graphics (r_picmip,vertex lighting,no gun, ect.), now it doesn't crash anymore, and i get a lot more fps