I thought I'd post this to see if anyone has an idea on how to fix this or if it can be fixed.

My Dreamcast acts kind of strangely: after 10 minutes of so of playing a game, it will start showing garbled graphics on the screen. If I keep trying to play much after that, it will lock up comletely. Inserting a new game doesn't work as it will almost always lock up immediately. The Dreamcast is sitting on a plastic CD rack to keep it well ventilated and doesn't seem to be particularly hot when these thing occur.