vista ipsec to cisco asa 5520

hi im trying to establish a connection from Vista Ultimate Sp1 64 bit to a cisco asa 5520 8.2 via l2tp ipsec

on the cisco i see

on the vista end it says in the log error 789...

this vista is at home behind a adsl and a netgear router....

BUT i'm able to establish a IPSec connection with Vista 32bit SP2 Business version over a public WLAN.

any hints?

thanks jan