Access 2000 multiuser application

You haven't given an indication of where these machines are located relative to the network connections and the server. Since the machines are, apparently, similar, I would suggest looking at two different areas.

What applications are loaded on each machine at startup? Perhaps your slow machines are running some applications in the background that are using member or even network bandwidth. Try getting slow machines to load nothing automatically so that you can start your application and be sure that nothing else is running.

The network is another area to review. Maybe the slower machines go through a different part of the network (different routers, etc.) and there are network problems, such as problems with the lookup tables inthe network hardware in the network backbone. One test would be to take a slow machine and move it to where a fast machine is located, disconnect the fast machine's network connection and plug the slow machine into that network connection. See if the application loads at a speed similar to the fast machine. If it does, then you definitely need to look at the network.

I assume that the icon/shortcut is exactly the same on each machine.

Always check the simple things (connections, settings, environmental factors, etc.) first.

Several possibilities:

Check what other applications are running at the time users attempt to load Access. CPU/memory load could affect load time.

Do the affected computers appear slow when other operations crossing the network are conducted (downlading other files from the server, email, Internet access, printing)? If not, this could point to an Access configuration issue.

Do the shells on the affected computers have all the same paramters as unaffected ones?

Where are the computers experiencing slow downloads located? Are they at the extreme limit (or maybe past it) for a physical ethernet segment (100m)?

Are the lastest NIC drivers loaded on these computers? Are all network settings correct?
Do the affected computers maybe have 10mb NICs? Even if they are 10/100 NICS, they may be having problems auto-negotiating connection speed. Try to force the NIC to 100mb (if possible - this option may not be available on all NICs).

Is the installed cable in fact Cat5? Do the cable segments for these slow computers run near sources of EMI (flourescent lights, power cables, moters, etc.)? EMI could cause an excess of rejected data packets.

What things do all the affected computers have in common (location, software load, hardware, etc.)?

You may need a network analyzer/packet sniffer to troubleshoot if all of the physical things appear to check out.