Hi Brian, and welcome to Vista Forums.
You might try doing a System Restore using a restore point dated before this problem to see if it can fix the problem. System Restore - How to
If not, then using Option One
in this tutorial below, check to see if the bad user accounts have a SID key
at the end of it in the registry. If it does, then follow the instructions in Option One to switch them. This will restore the backup and hopefully fix your problem for that user account. The User Profile Service failed the logon. User profile cannot be loaded.
Hope this helps,