Video drivers?
Or maybe you've installed the latest patch for unreal tournament (i didnt and my db works perfectly well).
Na dunno try reinstalling the 3339? patch (i dont remember) then deathball 2.3. should work
You may want to post this client issue in the general discussion forum. For the most part, only server admins look in here - I could be wrong though..
Also, the latest patch is 3355. You might try that as well. The thing that concerns me most is that you say your whole computer dies. That isn't so much indicative of a UT2004 problem as it says there may be something wrong with your computer. Perhaps your video hardware is overheating?