I recently received from a friend an IMac computer. It boots up fine but when it gets to the desktop everything freezes (mouse and keyboard). I power it off with the power button and I get a message about improper shutoff or system crash and it I suppose it scans the hard drive ( I know squat about Imacs). During this time I can move the mouse cursor and the keyboard works. However, once it begins to load the desktop, same thing, freezes. I am assuming something is corrupted and the easiest way is to reinstall/restore the system. The biggest problem is that my friend told me she does not have any CD's or disks for any kind and neither do I. The OS is 8.6. Where can I get a cd to reinstall/restore without costing me an arm and a leg? I live in Mesquite, Texas. Thanks to anyone who can help.