mapped drives disconnect

I have several networks running win2k pro clients. Some have WIN2k Server and some with NT4.0. I am getting random mapped drive disconnects. At one location (win2kserver) the same client disconnects several times a day. It seems to be random. I’ve changed the port on the switch, this changes nothing.
I didn’t build all of these networks (but most of them). I don’t think I am the only one with this problem but can’t find anybody else.
Any suggestions
Gordon
gordon@theautomatedoffice.com