Normally, System error 51 is sharing issue. Assuming other version windows VPN client doesn't have this issue, I would try to disable IPv6. Please post back with the result.

Bob Lin, MS-MVP, MCSE & CNE
Networking, Internet, Routing, VPN Troubleshooting on http://www.ChicagoTech.net
How to Setup Windows, Network, VPN & Remote Access on http://www.HowToNetworking.com
"Richard_G" <RichardG@discussions.microsoft.com> wrote in message news:80927010-C72C-44E3-AC34-48460F6E0016@microsoft.com...
Are any MVPs about to give their advice with regards to this problem?

"Mike Howells" wrote:

> It appears that numerous peopl are also having this problem with Vista. It
> is a big mystery at this point.
>
> I am very curious what the solution is to this problem because for me this
> is actually preventing work from getting done.
>
> Mike
>
> "pasflug" <pasflug@discussions.microsoft.com> wrote in message
> news:E72CAF56-512E-4180-B31B-5F7FA1478F7B@microsoft.com...
> > Hello,
> >
> > we are having the same problem with Vista Ultimate (final). I am trying to
> > map to a shared folder on the VPN server. Ping (ICMP) works as well as
> > HTTP.
> > I've deactivated alle Firewalls on the client machine, still nothing. I've
> > tried to analyse communication between the machines with Ethereal, but it
> > doesn't detect the VPN connection on Vista.
> >
> > Does anyone have a clue? Thanks for posting
> >
> > Pascal Hassenpflug
> >
> >
> >
> > "hdejongh" wrote:
> >
> >>
> >> Hello,
> >>
> >> I`m running vista rtm. I`m have a connection to my company through vpn,
> >> (win2k3)
> >>
> >> I`m unable to make any kind of network shares..
> >>
> >> I`m able to make all network shares on computers on my home network.
> >>
> >> I changed in secpol.msc:
> >>
> >> network security, lan manager authentication level to: send lm & ntlm
> >> if possibleblablbla
> >>
> >> well that`s kinda it...
> >>
> >> oh net view doesn`t work either
> >>
> >> C:\Users\xxxxx> net use * "'\\192.168.2.1\test'
> >> (file://\\192.168.2.1\test)"
> >> System error 51 has occurred.
> >> Windows cannot find the network path. Verify that the network path is
> >> correct an
> >> d the destination computer is not busy or turned off. If Windows still
> >> cannot fi
> >> nd the network path, contact your network administrator.
> >>
> >> C:\Users\xxxxxx>ping itcdc01
> >> Pinging itcdc01 [192.168.2.1] with 32 bytes of data:
> >> Reply from 192.168.2.1: bytes=32 time=9ms TTL=128
> >> Reply from 192.168.2.1: bytes=32 time=9ms TTL=128
> >>
> >> C:\Users\xxxxxxx>net use * "'\\itcdc01\gedeelde'
> >> (file://\\itcdc01\gedeelde) data"
> >> System error 51 has occurred.
> >> Windows cannot find the network path. Verify that the network path is
> >> correct an
> >> d the destination computer is not busy or turned off. If Windows still
> >> cannot fi
> >> nd the network path, contact your network administrator.
> >>
> >>
> >> --
> >> hdejongh
> >> ------------------------------------------------------------------------
> >> hdejongh's Profile: http://vista64.net/forums/member.php?userid=835
> >> View this thread: http://vista64.net/forums/showthread.php?t=27320
> >>
> >>
>
>