After pressing power button, computer will show initial loading screen with apple logo, loading symbol, and grey background for around 15 seconds before it restarts on its own and does the same thing again. Cannot get past this initial cycle. Any ideas/suggestions? Thanks.
iMac G5 Intel-based, Mac OS X (10.5.8)
Have you tried booting from the install disk that came with the Mac? Disk in drive and press the start button while holding down the 'C' key. If it boots you could try running Disk Utility from the Utilities menu.