What are the clients?

I have vague memories that the network redirector on older clients does not support IP addresses.

As you are using a VPN I assume that you cannot use WINS or DNS because that is set for the ISP that you have dialled into.

In this case Jens' other suggestion is your best bet.

When your script starts, update the local HOSTS and/or LMHOSTS with all the IP addresses that your client will need for the session. Include the DOMAIN information for LMHOSTS entries where appropriate. You may need to force a reload of the files.

Do this *before* you attempt any TCP or NetBIOS type connections to your netowrk, otherwise you may cache a negative response.

Of course, the client also needs to be configured to use the static address files...