powermac g4 display probs

[jteef]

so my friends UPS broke today and turned his mac off. When we powered it back up the picture on the screen came out inverted and in 256 colors. We found out where to change the color depth back, but this inverted thing is really weird. And by inverted i mean the colors are. Like if I open a picture in photoshop and "Invert Colors" the picture looks like it is supposed to, but the rest of the desktop is still messed up. Does anybody know what would cause this or how I can change it back? I know next to nothing about these things.

Thanks