This issue occurs due to the presence of Cisco bug ID CSCeb41256.
In order to resolve this issue, verify that the VPN Client version is 4.0.3.D or later. Then, add the vpnclient.ini value shown:
The default value for VAEnableAlt is 1. As an alternative, the ini value must be changed to 0, as shown.
VPN - hardware & software clients
VPN Client Software Version
VPN Tunnel End Points
Any end point