I have had this happen now with 2 different intel centrino wireless laptop adaptors (6200 on a sony vaio and 1000BGN on a lenovo)
Both laptops connect to the wireless and everything works fine except when connecting to the VPN servers.
I have ruled out everything else and the problem definitely lies with the intel wireless cards.
Both laptops are running windows 7 x64 and both laptops connect to the VPN servers using the wired network and also connect fine over wireless when I installed a wireless USB dongle.
The problem is when the VPN tries to verify the credentials, they are not passed via the wireless and the VPN connection sits there saying verifying username and password and eventually times out.
I have tried updating the drivers, but nothing seems to work.
I am having a similar issue. I have 2 Dell Latitude 6420's. They have Centrino 6205n cards in them. The users are able to connect to the VPN using Cisco VPN client but for whatever reason, the client machine uses the external DNS server rather than the VPN network DNS servers so they are unable to find anything (mail servers, intranet site etc) on the internal network.
Any other client machines that do not have Intel Centrino cards are fine.
Very strange issue......