Hi, just upgraded my 250gb hard drive to a Seagate 500gb Barracuda. I have been having some problems with the imac i get a kernel error to power off the unit and the fans are super loud I thought it was a bad power supply since all the LEDS are green. I swap it out and I still have the kernel error I tried resetting the memory thing by holding option, command and p r and still no luck. Any ideas? and thanks in advance.