puter keeps shutting off

[lindablueyes]

[freelobotomy]

[icecube]

If you computer is rebooting, it could be a heat issue as freelobotomy suggested. But if the computer is still running it could be a bios setting turning the monitor off after 30 minutes of inactivity, or a screen saver.

there are some known issues with 98 power saving modes messing things up. Change them to never (hard drive and monitor) and you might be ok

Also it could be a bad monitor. Or the cables connecting the monitor to the computer could be loose. Another thing to check would be the video card. It could be rising out of its slot and needs to be pushed in (that doesn't sound like your issue though). Also video cards do go bad.