Rose,
Most likely the group that you are trying to connect to on the ASA has the integrated firewall feature. This feature is not supported for windows Vista Clients.
You can disable this on the ASA by getting into the group polices:
ASA(config)# group-policy "VPN group name" attributes
ASA(config-group-policy)#client-firewall none
If you have other clients connecting fine and you don�t want to do this change, you can configure a new group for the Vista Clients without the integrated firewall feature.
Regards,
~JG
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