Hi guys, bought this iMac since Dec 07 and it is running very smoothly and i am enjoying it since then. My recent problem is : imac do not have any response after hitting return button after sleep. Usually when i try to use the computer after sleep, all i did was just hit any button to wake the computer up and everything is back to normal. The problem now is when i hit any button to wake the computer up - all i hear is a constant beep sound and a dark screen. I have to press the on / off button to restart the computer. Could anybody assists me with this problem cos i have never had this before until today. Thanking all help and clues in advance.