I am having problems with my I-Mac. It is the 2.8GHZ 24" model and when I try to start it up I get a white screen with a blinking grey file folder with a "?" mark in it?? I had this problem before. Erased the hard drive and then reinstalled everything. I made it through it but I think I may have done it wrong. Anyways the computer worked good till the other day. I upgraded to Snow Leopard and now it is doing it again. Do I need to start with the install disk 1 that came with the computer and install disk 2, then install snow leopard? Or can is there a faster route of doing this?