Unreal Tournament 2004 Restarts with a serious error

[Flak Master]

OK, for three days in a row, I've been making this map, and, while I haven't lost any progress, my PC keeps restarting for reasons I'm not totally sure on. When Windows XP boots back up, I get a message that a serious error occurred on all three occasions. They all only happened once each day, but I've got these messages before. The one I got an hour or two ago, when I checked it with this Windows Debugger program, was a "KERNEL_MODE_EXCEPTION_NOT_HANDLED_M"(1000008e ). I've read these errors have so many causes that I can't figure out which one it is. But, every time I got these errors, I was doing something either in UnrealEd or UT2004. I was going to change my character's voice pack, but, when I clicked the "Player" tab a few hours ago, my PC rebooted. Any idea on what is causing this to happen?

[GreatEmerald]

Most likely file or memory corruption. The only surefire way to solve those is to reinstall the OS and run the memtest program. If you want to try a less radical solution to the file corruption problem first, run chkdsk on all of your drives; but note that it's not guaranteed to work.