Posted 11 September 2008 - 09:37 AM
You might find that the firmware on your mac is not allowing the disc to boot. I'm not sure that Macs that can still run OS9 are able to run OS 10.4. Has your mac got a firewire port? This is a sure fire way of knowing whether 10.4 may be able to run. No firewire port = 10.4, also check the system requirements against what is in your machine.
To return your system to a more standard way of starting up you could clear the nvram and the pram.
To reset PRam
Hold down cmd + alt + p + r
before the grey screen as the machine is starting up, listen to it chime a couple of times to be safe then release the keys. This should return the machine to a more standard setting.