I bought a used iMac G5 17". The imac wouldn't boot and had the flashing question mark. I did a new install and erased the disk and it worked perfect. I then shipped this computer to a relative as a gift. When I went to set it up for them. It wouldn't boot up. The gray screen would appear with the little clock thing and then it would go to the blue screen and hang there. The mouse pointer is all that would be on the screen and it was functional. I tried rebooting to no avail. I then tried reloading the software and it would get about 20 minutes from the end of disk1 and without notice it would restart and again end up at the blue screen. I ran the disk utility and did a hardware check. Initially the hardware checked showed a memory error with the 512MB board, so I pulled that out and it passed the test with just the 1024MB board in place. I tried reloading the operating system again, and again it did the restart again and stopped at the blue screen. I'm out of ideas on this. Does anyone have any?