iMac won't boot from HDD or CD. Help!?
I recently came back from holiday for a couple of weeks and sat down to start my iMac (24" C2D). The machine just sat at a white screen and wouldn't go anywhere. Thought, ah, I'll just reset the PRAM (unplugged power cable for a min or so), and still same problem. Eventually I got the mac to boot by holding down the power button, the long beep sounded and the mac booted. All was well, until the next time I powered it down. Same thing, however same resolution didnt work...
After numerous attempts holding c, I've managed to boot into the mac installer, which said it couldnt repair the drive through disk utility. As I have time machine backup, thought I'll just start from scratch. Created a new partition (just to make sure everything was fresh), verified disk (no problems), started installer and it crashed towards the very end of the install (just over 1 hour in) with errors of being unable to copy files. After another few hours, managed to boot from CD again, this time install started, left it running overnight, only to find the mac in the morning on, but with a black screen. I've had to power it off and now I'm left with the same issue of a white screen and being unable to boot from CD.
Does any of this make sense to anyone? Could be a failed HDD, but why would I have the issue with the iMac generally refusing to boot from CD? Ran hardware diagnostic (extended) and no problems found.
I now have no hair left...
iMac, Mac OS X (10.5.6)