WIN2K and USR 5610A

I have a user that is running W2K upgrade with a USR 5610A modem that after using on first instance of dialing out breaks connection and attempts to re-connect modem dials out but is unable to establish connection. When using VPN and discontinues VPN instead of being able to continue using ISP can no longer use connection…needs to reboot. Has anyone else run into this problem? And, if so, found a solution?