GOT IT!!!

PORT 3050 ADDED to windows firewall!

Now the newserver:c:\prax\prax.fdb works on all PC's all users!

Thanks to everybody who helped.
I learned a vast amount:

1). Don't share drives, folders to get things to work! They don't need to be
shared! "The owner of the server process in Windows is (by default) the
LocalSystem user, which has huge privileges. In short, unless you installed
Fb 1.5 to be owned by a different user than LocalSystem, permissions won't
be the problem. FB-GURU"
2). Make sure ALL the PC's are running the same version of Firebird!
3). Make sure you have set up your hosts file with the correct IP address
pointing to the server.
4). Don't use *.gdb with firebird .. rename *.fdb: " This has been
documented to death, across two releases and about a gazillion times across
the support lists. FB-GURU"
5). Open a port in the firewall on your server for the STANDARD firebird
port: 3050, or if you are using something else, then open that port.
6). Meticulously check for typo's, in pathnames, config files, hosts files.
7). When you don't succeed try, try again, ask, ask again ..you will
succeed!
8). When making changes to the firbird.conf, stop - restart the server for
these to take effect.

Adrian