Hi guys, My 24-inch early 2008 iMac's screen has gone light gray twice in 24 hours. Here are its specs: Am running Lion 10.7.3 and also have an 18-month old 320GB SATA hard drive, which replaced the original one after it failed. The only thing I can do is reboot using the power button. The odd thing is, my Mac has been really slow the past six months and I've just been putting up with it. But the fast few days, it's been running really fast while doing lots of mildly intensive stuff: running InDesign, Photoshop, Illustrator, iTunes, Safari, Pages, and Mail. It was running really quick, which is odd, because it normally slows with just Photoshop running. But then I get these gray screens, which admittedly I've got before — once in a blue moon on isolated occasions. Searching doesn't turn up much. People talk of the gray screen of death, but this doesn't seem to be it as I can no restart warning or anything. Your help is really appreciated! Thanks.