Cannot save to mapped drive

I have a drive mapped to a folder on my hard. If I navigate directly to this
folder I can open a doc, change it and file it back to the same location.

I have mapped access to the same folder as drive "X". When I access the very
same file via the mapped drive I cannot save back to the same location. When
I look at the permissions tab I do not see any reason I could not save to
this folder.

How to fix?

By the way... this folder is in my "Public" folder and I have mapped access
to it for my wife's computer. I have set full read write access for her in
this folder but she cannot make changes using either the mapped drive on her
computer or by navigating directly to the folder via our home network.

Also... I recently reinstalled Vista on this PC. Both me and my wife were
able to make document changes and save them using the mapped drive before
this.