MacMini - strange fonts/color but only after session start

My MacMini (non Intel) is being really odd. When I start up the appearance of colors and fonts is picture perfect as usual. But when my session actually starts the desktop image seems to lose colors and the fonts are washed out and blurred. I've tried the font smoothing dialog, and logged out and in of my user session, re-started my machine etc but no joy. I have a ViewSonic monitor. Any ideas?



This issue happened after I inserted a bad CD into the drive and then had problems removing it. It's out now thanks to advice on this bulletin board. The oddest thing is that it really does look fine and normal for a few moments before looking bad.



Thanks!