I have a 24" 2.66 Ghz intel core 2 duo imac with 4GB RAM. I went to start it up this morning and all I got was the white/grey screen with the little pinwheel. After searching on line all day I came across many different supposed fixes for the problem. ***One was to hold "Command + R" at the start up to boot it into a disk utilities mode to repair the error. ***Another was to zap the pram by holding "Option + Command + P + R" at the start up. ***Another was to hold down the "Shift" button which brought up this screen... Please see attached photo by clicking on the link... http://imageshack.com/a/img24/8362/6e1k.jpg As you can see, there was a bar at the bottom, which seemed to be a processing of some sort, but when it was complete, nothing happened. ***Another was to hold "Shift + Command + V" which brought up this screen... Please see attached picture for a detail of the information... http://imageshack.com/a/img844/8036/pzio.jpg As you can see there seems to be some errors of some sort. Does anyone know what "Invalid node structure" means? Or "Invalid record count?" Or what a disk)s2: I/O error is? I tried looking some of these things up on line but couldn't find much or much help in trying to repair them. Does anyone know how to fix this problem? ***Another thing I tried to do was re-install my OS by holding down the "C" button with the Leopard disk in, which failed and now my mac has my OS disk inside the machine and I can't seem to get it out. I would like to avoid bringing my Mac to the Mac store. I also tried everything on this link http://support.apple.com/kb/TS2570 I unplugged everything in between many times on start up and nothing worked. I didn't try to preform an erase and install, which I also want to avoid. Does anyone have any ideas on how to fix this problem?