OK... I have a late 2009 27" iMac G7 which has been great... until yesterday. For some reason now after restarting, the display will not stay on. The system boots ok (i get the startup chime) but immediately after this the screen display goes off (like it's in sleep). If I hit the F11/F12 volume control keys on the keyboard I get the increasing/decreasing beeps, so I know the OS is up & running. Also if I wait a few mins and hit a key on the keyboard the screen wakes up and I get the login box (my iMac is secured by password) and I can type in it, but only for a couple of seconds, then the screen goes off again. Have tried PRAM/NVRAM resets etc, but nothing works. It is still covered under AppleCare but I know they will just tell me to take it to my nearest Apple shop (40 miles away) and then wait the usual 10-28 days for them to fix it. Would like to know if there's anyone else has experienced this and if there's a simple solution. Everything seems to be working OK, but the display just won't stay on. Thanks all.