I have a PowerMac G4 Titanium 867mhz running OSX tiger 10.47. Recently I have been seeing the spinning rainbow a lot. Today I installed the gmail notifier tool from Google and tried to reboot but everytime OSX displayed the logon interface the machine froze giving this message "you need to restart your computer". Now I wanted to reinstall OSX but I couldn't get to the appropriate screen.I tried holding down the "c" key, when that also failed I tried to reset the PRAM by holding down the option+command+P+R keys still no show.I need help desperately.Thank you.