Tree or Server Cannot be found on second login

We have a DELL Dimension 8400 configured as a VPN client that fails to
login a second time to the site.

The first login after the restart of the computer always goes well.
Rarely a second or a third login attempt will also succeed but that is the
Users get "The Tree or Server cannot be found. Choose another server or
tree" errors on all future login attempts!
If you look at the VPN tab on the novell login window you see that the
check mark on Enable VPN box is gone and the configuration parameters are
also grayed out.

All of a our computers that are of other manufacture configured as vpn
clients in the same way can perform unlimited nr. of logins to the site.

Client: OS: Windows XP SP1
Novell Client: 4.83 SP2
VPN client: Novell Border Manager VPN Client 3.7.3 (LAN)
NIC: Broadcom ---> BCM57xx

Novell Border Manager 3.7