Vista - Net View Mystery

I connect to a customers network by VPN (PPTP) several times a day to audit
certain network usage information.

The following command works on the first VPN connection only
net view /DOMAIN:CUSTDOMAIN

If I log off the VPN and then reconnect (whether anytime later in the day or
immediately) and run the same net view command it always fails - usually
with the following error.
System error 2 has occurred.
The system cannot find the file specified.

For it to work again Vista must be rebooted. Interestingly this problem
does not occur in XP, but only in Vista. Any ideas on why are welcome.