This issue occurs occasionally, as if the logging in user has never logged into a machine before. The old profile is still in in Documents and Settings, along with the newly created profile. Suspicions point to ntuser.dat becoming corrupted.
How to return to the old profile
1.Go to Documents And Settings, and determine which is the old profile. One or more of these exist.
Sometimes opnening a well used profile’s desktop will give a clue, other times looking in the outlook folder for a .pif file will clarify which is the correct one.
2. Delete or rename the incorrect profiles.
3. Start–> Run –> Regedt32
HKLM\Software\Microsoft\Windows NT\Current Version\Profile List
This is where each SID is stored for the list of profiles on the machine.
4. Find the path to an incorrect profile . Edit the location in the ProfileImagePath key to reflect the profile identified in step 1.
Log out, and have the user login. The issue should now be corrected.