Reboot, Press F8, select safemode, restore to an earlier date and then reboot and try to login in.
or if that dont work
log onto the administrator account (it's good to be the king sometimes) and examined the keys under HKLM\Software\Microsoft\WindowsNT\Current
User\ProfileList\ and was able to find the key for my user id SID. Sure
enough, the key had a ".bak" appended to it and there was an identical one that was set to a temp directory. I renamed the other key, removed the ".bak" from mine, and changed the State property under my key to 0. And this shud allow you to login