I've got a BM3.8Sp2 server (running on NW6.5SP2) set-up with client to
site VPN. A while ago it was working fine.

I've now tried to use it in anger, and whenever I click the connet
button in the VPN client, the client thinks for a second or so, and then
jumps back to the VPN tab.

WHere do I start if troubleshooting or fixing this ?