MAC OSX 10 not starting up


I have a Apple G4 500 mhz dual and i just did the update that apple gave me in the "softwear update" and now my computer doesnt want to start. i have tried starting it up with the install disk but i keep getting the msg to restart the computer.

The mac goes thru all the start up and then when i go to logo on it goes gray and tells me to restart. please help!

Thank You