PowerPC :: G4 That Goes To Sleep Every 10 Seconds

My roomate as a powerbook g4 1.5ghz, it had been running 10.4.8. The computer will go into sleep mode randomly about every 10-15 seconds. Doesn't matter what program he's using. If he leaves the comp off for a few hours, it wont do it for a while and he can use it. Only thing we've found online is that people had that problem when they had faulty trackpads/trackpad sensors. But we don't think that is the issue we weren't getting an error message as they were in the console when it would occur. We called a local mac shop and they said it'd be 100 bucks to diagnose the problem, and probably it sounded like he would need a new logic board for another 700 + Labour.

A friend at school had the Apple Service Diagnostics 2.5.8 boot disk. He told us to give it a shot rather than paying the 100 bucks to get it "checked out" as it would most likely tell us what, if anything was wrong. We ran it, all hardware and software tests passed w/o any errors. We even tried doing a full format and reinstall of OS X 10.4.1, it got through the install procedure, and it seemed to be working ok for about 30 minutes, then suddenly the problem started again! So I that makes me think its not software related. So far two software "tests" and one full ASD hardware test got us nowhere. He's tried a lot of stuff he found online, but nothing has worked. Such as resetting all the various rams and sensors and PMU.