imac g4 doesn't want to boot

Not sure if this is the correct forum or not but here goes. When I started up my mac this morning I received an error message saying "invalid memory access at %sr00............". Mac Support said to try apple option p+r, did that, no luck, and then I tried to do repairs starting with disk permissions. This is where the real trouble began. The system locked up and got stuck with the spinning pinwheel, would not force quit so I powered down manualy. Start up now went to apple logo screen and hung there. After another restart I went back into install disk to do a archive and install, but when I get to the selct destination disk screen there are no choices. I am stumped. Any help is appreciated and sorry for the lengthy synopsis.