Looks like your user has lost their profile. Log in as someone else and check to see if there are more than one folder under documents and settings for the user having the issue. If you are lucky the users profile is still there and the pc created a new one. I have had issues where a single file gets locked out by windows and the profile becomes broken. Windows creates a new one. If that is the case and you see two similar usernamed folders under c:\documents and settings\ then you will need to reset security on the old folder. I would hazard to say you could also copy it to a different location and then rename the new profile to username.old and then let the user log in again.
That said if you don’t want to waste so much time you can just recreate the settings under the new profile.
<a href=”http://support.microsoft.com/kb/307910″>Upgrades and User Accounts</a>
<a href=”http://support.microsoft.com/kb/174491″>Various Profile Scenarios</a>