For the longest time, FileMaker Pro 6 was setup as a Multi-User File,
and people could then access it. Just recently, when you open File
Maker Pro 6, on the server (which is where it's always been, and never
gets touched), it brings up an error with the following text.

"FileMaker cannot host a file because of a network error. Files marked
as Multi-User will not be available over the network. (10048)"

I've used the FileMaker Pro web site, and Googled to no avail. I know
that it uses port 5003 for communication. With FileMaker Pro 6 closed,
if I do "telnet 192.168.1.4 5003) - the IP of the server, it connects
(ie: black terminal window, but that's it). That suggests the
connection is open. When I open FileMaker Pro 6, it gives the same
thing. So, somehow - that port is not getting closed, and so when I
open FileMaker Pro 6, it's already open and won't work as it used to.

Any ideas on how to solve that?

Adam