Don't forget the other color screens that can pop up. A grey screen (can be light or dark grey) - put it out of its missery - something serious and deep has happened.
A blue screen can happen, which means one of the custom chips is in trouble.
The red screen can be one of several problems - it can be a ROM error, or a bad card (press both mouse buttons to see what it says (if you're using OS 3->) on startup (boot menu)).
