I have a 2008 Aluminum iMac, which intermittently won't start (with a disk not found question mark), and which, when started, sometimes freezes irresolvably. Because of the missing disk indication, I thought it might be a problem with the hard drive, but Disk Utility, fsck and a full, extended hardware test all reported no problems. Could this be a problem with the HDD cable? I see that some MBPs have been reported with this, but I'm not sure if it's a likely culprit for this iMac. My current inclination is to try replacing the HDD cable and see what happens. A bit more information on the hardware test. The only error it reported was this: 4MOT/1/40000003: HDD-1348 - which seems to refer to the HDD fan motor. However, using Smc fan control, I can control the fans in the machine, and hear each one working independently, so I'm not sure what this error is about. The other thing I should mention is that not long before this started happening, I upgraded it from Leopard to Snow Leopard. This wouldn't be my first source of suspicion since it looks very like a hardware issue, but who knows.. Any advice or opinions very much appreciated. Thanks!