Okay guys, this is a shot in the dark but I'm pretty much desperate at this point. I'm going to repost here what I posed on Apple's support boards. Here's the deal, after installing Leopard I could not log into any of my accounts. When I log in, it goes to either a blue background or the Leopard background. Booted up Leopard disc to repair both startup disk and permissions to see if that was a problem. I also set a the firmware password. I then reinstalled Leopard. When I booted up, not only did the accounts not login as before, but when I tried to restart from the Leopard disk, it would not boot up from the DVD. Tried the tiger DVD that came with my iMac, didn't work either. I then tried to reset the PRAM, boot up in single user mode, and even tried starting up to firmware as a last resort, no startup commands work. I honestly don't know what else to try. If it helps at all, my master account was imported from my old ibook which shipped with 10.2.