To fix this issue you can go here at the Microsoft help and Support page
The Automatic Tool - Microsoft Fix It For This Issue HereHowever sometime the above does not work and there is the alternative way below which hasn't failed yet!
well for me anyway
If there is another administrator account that you can log into, then jump to step 7 after logging into that account.
However, if you can't get to any accounts at all, then start at step 1.
1. Restart your computer and hit F8 multiples times until you see a menu-like screen, if you see the Windows splash screen then repeat this step
2. Highlight and hit enter on Safe Mode with Command Prompt. Try logging in there. If it still doesn't work, then go to step17
3. If you are able to login, once a command prompt pops up, type: net user administrator password /active:yes (you can specify whatever password you want for the administrator account.)
4. If you get a message saying "The command completed successfully", then restart your computer by typing: shutdown -r
5. Boot up again pressing F8, but this time choose just Safe Mode.
6. You will be able to login as Administrator with the password you set in Step 3
7.Hit (windows logo)+R
8. Type regedit
9. Once the registry editor opens up, look for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
10. In the left pane, find the one that starts with S-1-5..... and ends with .BAK; if you don't find one, skip to step 15
11. Right click it and click Rename, then change the .BAK to .BK
12. Right click the one with the same numbering but without the .BAK and add .BAK add the end
13. Right click the one that you renamed to .BK and clickRename, delete the .BK
14. Eventually, you have switched the .BAK from the end of the second entry to the first. That should probably fix your problem.
15. If you didn't find a .BAK then try this: Open Windows Explorer to C:\Users\Default\AppData\Local\Application Data
16. If you find another Application Data below the one you're on, then delete it. That should probably also fix your problem.
Hope this fixes your issue
Edited by Bugsy, 13 May 2011 - 10:38 AM.