I'm not sure if anyone will be able to answer this question, its kind of a tricky one. I have an IMac its an early 2008 Core 2 Duo 2.4Ghz, with 4 gigs of memory. Recently i was working on it and the screen went black, i was attempting to figure out what was happening and finally i narrowed it down to the fact it would randomly shutdown then try to restart, in most cases it would just keeping trying to restart, like i would hear the disk drive and fans starts, then a second later before it even could it would try to restart again. I have recent the SMC by unplugging and holding the power button for 5 seconds or so. After doing this the computer will start up again without falling into that loop of restarts it did before, but eventually it will do the same thing again. I have even tried to boot to my Windows 7 partition, but eventually it still just shutdown and tried to reboot. It seems to me it either has to be a firmware/kernel level problem, or a physical hardware problem. I was mainly wondering if anyone else has ever run into this problem, also i have checked all the temp levels on the computer in the few minutes it runs, and they all look acceptable. Oh and as a side note if i boot it up after resetting the SMC and it works for a bit, if i do put it to sleep manually it will sleep, but the second i try to take it out of sleep by hitting a button or moving the mouse, it just restarts again. This leads me to believe it has to be related to the monitor? Any suggestions or info will help, and i have gone though all the simple steps of resetting the pram, and SMC. So those help for a few then it will crap out on me. Thanks Much!