This has happened mostly on my samba domains, I can't remember specifically if it occurred for me on a true Win domain but it probably has. The issue exhibited itself when a user logs in and is given the profile path of "C:\Documents and Settings\TEMP" which is created when the user logs in. No disk errors in the event viewer, and the users profile still exists and is readable by the user. I tried renaming their profile so they would get a new blank one, but it persisted going to TEMP, so it was not simply a file access error. This has occurred in Win2k, 2k3 and xp.
The fix:
Install the "User Profile Hive Cleanup Service" from M$ and logoff the effected user and reboot and their profile works again.
http://www.microsoft.com/downloads/details.aspx?FamilyId=1B286E6D-8912-4E18-B570-42470E2F3582&displaylang=enIn other cases, I might have attributed it to a virus or spyware. Sometimes I would just rebuild their profile and copy/paste the data. But this one user had it happen to them only a month after getting a brand new computer which otherwise ran like a dream. So I didn't want to 'give up' on this one.
This also helps keep the event viewer clean of the CONSTANT errors about the user profile not unloading completely.
I am posting this for the benefit of the community, hopefully it will help prevent unnecessary Google hunting.