Hi,
even though this question is probably too old to remain as an issue, I am pretty sure some people facing the same issue end up here.
I had the same problem with my Nortel VPN client. Upgrading to 10.04.109 did not solve the issue.
Checking the services (right click on my computer-manage-services and applications-services) I have realized that the service for "IKE and AuthIP IPsec Keying" was not started and could not be started, because the service "Base Filtering Engine" was missing completely.
I have therefore exported both the BFE Keys and the IKEEXT from the registry of another computer, and imported them to the registry on mine.
Finally I had to add a new user under permissions for the BFE key in the registry. The user name is NT/BFE and it should have full access rights.
This has solved my issue and my VPN is fully functional again!!
Hope this helps