XP Wireless & VPN Issue

[WhoIsThatGuy]

I have noticed something real strange with XP and XP with SP1 installed. The wireless uses WEP to gain access to an isolated network that is routed to the VPN server, after a wireless IP has been assigned, the user starts the VPN connection. The VPN server grants access to the internal network through regular user credentials. All Win2K clients and XP clients without SP1 installed do not have a connection issue. XP clients with SP1 get the wireless IP, and they can start the VPN connection, but they are not authenticated into to the internal network.

Any ideas on how to solve this????