Mac mini & OS X Start-up problems

[TrojanBabe]

Whenever I turn on my Mac mini, it plays the usual music clip, but then the screen goes black and text pops up saying "No bootable device - insert boot disk and press any key". So I inserted the OS X Install disk that came with my Mac and restarted the Mac. The exact same thing happens even with the disk in. I have tried the commands to eject the disk, go into safe mode and all the other options but it doesnt get any further than this. It's an Intel Mac mini, 1.66 Ghz (Core Duo), 512mb Ram and is running OS X 10.4.10. It has a 60GB hard drive with about 200mb space left. Everything is up to date and I havent installed anything recently. I am using a Windows usb keyboard and a wireless Apple mighty mouse. The Mac was bought in February 2007 and hasn't had any problems in the past.

[Twenty20]

You used to have to start up whilst holding down the 'c' key on the keyboard to restart from a cd or dvd. Have you tried that?