Farruca,
Not really sure how this could be accomplished without some bad side
effects. Off of the top of my head, you might consider disabling their use
of 'net' via GPO - but that might prevent them from being able to make use
of any logon scripts.
You could try hiding all of the shares with an appended $ at the end of the
share name so that they can not see the shared folders when browsing the
network. But this is more administration with the hopes of user ignorance -
which typically does not really work. There will always be at least one guy
who thinks he is smarter than you are and will figure this sort of thing
out.
What is it that you are trying to prevent ( okay, at first glance that is
obvious - what is behind this )? Not trying to pry, just trying to get to
the root issue.
HTH,
Cary