XP requires password that was never set

Ok, here's the deal. Updated my AVG Free to 8.0, made a restore point, ran it and rebooted. No problems. Then I made another restore point, and ran Registry Healer. Now I have been using this program for years on different machines with no problems. After it ran I told it to correct all picked items. I only had the items the program denoted as picked. Then I rebooted. That is when my problems started. When I rebooted the computer prompted me for a user password. Well, none have ever been set, so leave it blank and hit enter. No luck. Told me I was restricted (sorry don't have the exact message). So, I booted in safe mode. This time it gave me the choice of owner or administrator accounts. Again, it wants a password that was never set up. Left it blank again and tried that, but once again no luck. I do not have the boot CD that came with the computer.

If anyone can point me in the right direction I would really appreciate it. I really don't know what to do at this point.