Vista - no ndiswan miniport, no vpn

hallo,

i experience a problem with vpn in vista.
when i create a new outgoing pptp-connection, vista creates a
dial-up-connection.

i assume that the reason is that the ras management service is not in state
started.
in the event log id 20027 from rasman with "ndiswan could not be opened" is
logged.
in the command prompt "sc state ndiswan" results inter alia in
"win_exit_code 1077 (0x435)" and "sc start ndiswan" in "error 1058".

when i compare the entries in hklm\system\current control
set\services\ndiswan with those from a vista-system where vpn works for me, i
see no notable difference.

i experience the problem on a hp nx9020, with no other problems with vista,
except that i have not yet found a working driver for the installed modem.
installing a "dummy-driver" did not solve the problem. i tried to reinstall
the network stack (removed protocols from nic, deinstalled nic, rebooted),
but with vista that does not seem to reinstall the stack. maybe there is
another method?

does please anyone have any ideas?
if not - is there a pptp-client for windows anywhere out there? i haven't
found one.

thank you..