XP won’t all write of shared files

One computer on network has a strange permissions problem. My Documents and Main Drive have been shared giving everyone else on network full permissions.

Any file can be opened and altered, but when a save is attempted it comes up as “read only”. Attributes view the file as archived.

I’ve been through all the usual: Permissions, Advanced, etc. Only people listed are the user herself, administrator, and everyone. If we add others to either permissions or sharing then the files can’t even be accessed.

XP Pro.