Anil,
Check this link and try the workaround see if this may help.
http://www.cisco.com/en/US/products/sw/secursw/ps2308/prod_release_note09186a0080884df5.html
Quote from link!
CSCsi26229, CSCsf07334
Vista: integrated firewall not installed on Vista.
When connecting to a group that requires the firewall on Vista, the client terminates the connection due to Firewall policy mismatch.
Workaround
Do one of the following:
-Disable the firewall check on for that group on the VPN appliance.
-Clear a custom DLL check looking for the Microsoft Firewall DLLS.
-Use an alternative Firewall that is supported on Vista and by the VPN appliance.
CPP pushes do not work for any Firewalls other then ZoneLabs. If or when ZoneLabs releases ZoneAlarm for Vista, customers can install this to get CPP support.
Rgds
-Jorge
Jorge Rodriguez