My apologies if this is a common thread or is inappropriately posted in the wrong section. I have an iMac Intel Core Duo that I bought roughly 3 years ago and it's running Mac OS X 10.5.7. Lately when I've started up the computer it immediately makes clicking noises and fails to locate the startup disk. I've ran Disk Utility and got no indication that anything was wrong and I ran a hardware check with the install disc and got nothing there either. SMART status is verified too. If anyone has suggestions (aside from backing up files) it would be greatly appreciated.