My iMac was running Snow Leopard and Windows 7 via Boot Camp successfully with no issues until yesterday. The iMac froze in Snow Leopard and I had to manually reboot by holding down power button. Since then OS X won't run, Windows is still OK. If I select OS X the iMac freezes on the grey screen. I've tried safe mode and still no joy. If I place my OS X 10.6 install disk in it reads the disk, stays on the grey screen and after 2 minutes I then get the Kernel panic screen to reboot. Tried on a 10.5 Install disk in case disk is the problem but it does the same thing (windows install disk works fine, so DVD player OK). Have also reset PROM. Rebooted machine using cmd S into Linux to check disk and it found no issues. Anyone got any other ideas. I have a full time machine backup so trashing the hard disk if I could would be OK.