The other night I updated my iTunes to the latest version (through Software Update) when I came to turn on my computer I was greeted with the dreaded white screen of death.

I use an early 2008 iMac 24".

I've tried the basic things, unplugging/turning off accessories, trying to boot from the install disk, reseting pram, etc, etc.

Still no luck and no change what-so-ever.

All I've been able to ascertain that my keyboard still works (by ejecting).

I should point out that I did recently replace my Hard drive with a Western Digital Black 500GB (though the computer is well out of warrenty) and I'm a little concerned that the problem could be the screen.

Update (18/05/10): I've been told that I could be getting the White/Grey screen of death because the optical flex cable is damaged (aparently this is common). Apparently the Optical Drive is part of the POST sequence, and an inability to read the drive can result in failure for the system to move on to other bootable volumes. More info here. I will disable the optical drive and see if that works.