VPN connection being bumped off

HELP!! 🙂

Background: I have a remote office using client to site vpn, via Windows XP PPTP to Windows 2003 Server. Internet service is DSL provided by AT&T/Yahoo at 6MB down and 768Kb up. Network hardware is Motorola DSL modem > Linksys Cable/DSL Router BEFSR41 > Dell PowerConnect 2724 managed switch.

Issue: When one user connects up via the vpn everything works fine. If another user attempts to connect to the vpn it kicks the first user off the vpn and establishes the new vpn connection. This is my only office with this issue, I have other remote offices with multiple users that connect via vpn and they don’t have this issue.

I’m scratching my head here and any help would be appreciated.

Thanks,
MarkHark