permissions issue accessing cygwin nfs server from linux machine

Hello everyone,
I have an nfs server running over cygwin on a XP-Pro box and a SUSE linux machine that needs to access
certain disks on the XP box. I set the uids, and gids on the cygwin machine to match those on the linux
machine for users that need access (and made sure all others do not map). I am able to mount the
XP nfs shares from the linux machine, and the owner, group, and permissions map correctly insofar as 'ls'
indicates. However, it appears that some users can write to areas of the XP that they should not be able to
and vice versa. Interestingly, all files created by users are automatically owned by root and are become part
of the users group. Root maps to an administrator account on the XP machine via /etc/passwd in cygwin. I also
tried using a map_static flag in the exports directory, but that had no effect.

I'm curious, has anybody has ever encountered this sort of thing before? Anyone have an idea how
to resolve this?

Thanks for any help.