Denis

A very obvous question but which machine is the boss on your network? Did you switch on the server before all the other pcs, or have you a situation I have seen recently where the network's master browser has been switched off?

Is file and printer sharing enabled on the workstations? If so why? Are all machines running with the same speed network cards? Are you useing a hub or a switch? Are all applications equally slow across the network or just your database? Is there any obvious difference between the speed with one workstation running and all of them? When was your entire network last restarted?

What network protocols are you running?

There are many more questions I could ask but to be honest without seeing what you are experiencing the questions are guesses.

Colin