greetings. hey it's my first time here and i'm loving it. this is a great thread. hope this information helps you out or atleast gets you to where the answers are. Roxio put out an update to their Adaptec software and it's crippling Windows2000 users to where W2K sometimes won't even boot. The fact that you're able to run for 20 minutes should be amazing. Anyway. Roxio was last reported to be working feverishly on a patch for W2K users. Check out their site often for an available update. Roxio's CEO even reported that Roxio's Tech Support is available 24/7 to all users that need support any which way Roxio can help with this problem until it's solved.
With this in mind, I really don't think you're having a "heat" problem.. If it were heat I would expect the PC to stay unrebootable for atleast 15-20 minutes for the CPU or other component to cool down.
Good Luck.