Hi, I am a new forum member, I have looked at some of the advice and tried the 'cmd, alt, p r' option and still no progress. I also get a slot type diagram at the bottom of the screen, mine is a 2007 iMac, upgraded memory and now on Lion. It had been working well, nobody has done anything, it has been running normally. Any ideas on how to get in to my computer? I have a Snow Leopard CD but I don't think. Have any other discs, it is a long time ago! I am not very technical so simple advice please. Also I am in Dubai so we have no official Apple support.