You could try zapping the PRAM because my suggestion would have been to use the system software installer disk to startup (do this by holding the "C" key while starting up) and then it could find your system folder that way, but I noticed that you said you can't find the disk. So, to zap it, while starting up your mac hold down Ctrl, Opt, P, and R (yes at the same time
) don't let go until the startup screen comes up.
I think my G4 started up every single time with a nice little flashing folder (although mine would actually start up and run even) until I got OSX Jaguar. Now, it runs great, but I don't have 9 installed anymore either.
Hopefully this helps or something helps... can't have a sick Mac out there.
Woops, I guess I should have read the whole thing... sorry.
Have you tried starting it up with the extensions turned off?? (Start up with the shift key held down.) All this does is turn off the extensions, which you can turn back on while you are there and then restart and they will be back on again. Not sure if it could be an extension conflict, unless you just recently installed something new.