I have been using ZA Pro and ZA ISS for several years with very few problems.
Recently, I upgraded ZA ISS to 8.0.298 and now I can no longer make a connection with Nortel VPN client.
This worked fine with prior versions.
Uninstall ZA ISS and the VPN client works fine.
Lenovo Thinkpad T60, WinXP Pro SP2 and latest updates