I have one of the older intel core 2 duo white 24" iMacs. Have had no problems with it but a few days ago I left it to go to sleep for a few hours and now have no monitor. It comes on, power light glows, makes the coming on noise, whirs and clicks and if I plug my iPhone into it, it starts charging and even tethers but the screen remains completely black. It may not be relevant but I downloaded and installed Lion a few months ago. Since then it has done one or two odd things like saying its not tethered when it is and twice I've done a disc and permission check with alarming results. It have repaired them. I know there are a few issues regarding Lion but it may be coincidence. I have removed and cleaned the memory cards. Can anyone tell me how I can check if this is a software or hardware problem. I'm in Spain and not very confident about how easy it will be to get it repaired by Apple. Any suggestions would be welcome.