Last weekend sometime, while Windows Vista with SP1 was working but UAC was disabled, possibly, a user's desktop became "C:\Windows\system32\config\systemprofile\Desktop".Now, this user has two desktop folders, 2 favorites, 2, music, 2 pictures and 2 videos. 1 under user\login and 1 under sys32\...userprofile.
changes to the users desktop, with UAC on or off, changes the ....\userprofile\desktop
other user accounts on same aren't hosed
Also, a grep for values in user's app data folder starts a loop centered around "Application Data" which regens the folder chain outward until the path becomes too long and fails.
A starting point for research please?!?
On a laptop that must be shared, by the way.