I have the first model iMac that went with the glass screen and silver and black modeling. Last night I left my computer on like usual and this morning I wake it up and everything is frozen. I couldn't do anything so I rebooted the computer. The computer starts to boot with the gray screen but for a long time. The Apple logo finally appears and then after a while disappears again and it just sits at the gray screen. I've hooked up my iMac to another iMac and can connect to the hard drive through firewire. I am backing up necessary files now. So I assume it is not hard drive issue, but possibly the mother board or graphics card? It is currently running the latest OS X 10.5.6(?). Whichever is the latest. Anyone know what the problem might be before I take it into a Mac store? Any possible solutions to get it to finally boot up?