Can specialfolderpath(26) be blocked for write access?

[Richard Miller]

I have one user in which my revlet is attempting to create a folder 
within specialfolderpath(26) [the AppData location], but it does not get 
created. I've tried it numerous times. It just won't go through. This is 
on a Vista machine.

Under what conditions can this possibly happen? I thought this AppData 
folder was a safe and unrestricted folder to write to? Can this be 
blocked by Vista itself or by some other program?

If this folder is not reliable, where would one guess IS a safe place to 
create a folder and store files under Vista? This same user's computer 
has the DOCUMENTS folder blocked for writing as well.

Thanks.
Richard Miller