Windows 7 automatically logs out when logging in
Solution 1:
The solution is simple: abandon ship.
His old profile is shot. Especially if it is as elusive of a problem as this, you have no idea what else is broken even if you manage to get logged in. Who knows how long it will be before you are troubleshooting Yet Another Profile Issue.
Use the new profile. Drag and drop his data files. Some programs may have to be reinstalled (if they were installed to the current user, rather than All Users).