I had a Vista Virtual Machine (VM) that had its domain profile active
when I joined it to a domain . This implies that it was able to
contact he Domain Controller [which is a Windows 2000 Server]
This VM was suspended for 2 weeks...
Now, after resuming it, it is using its Standard Profile.
I ran the command : gpupdate /force to force an update of Group Policy

The Group Policy update failed with this error -
The processing of Group Policy failed because of lack of network
connectivity to a domain controller. This may be a transient
condition. A success message would be generated once the machine gets
connected to the domain controller and Group Policy has successfully
processed. If you do not see a success message for several hours, then
contact your system administrator.

What settings have changed on the virtual machine or on the Domain
Controller to cause this?

I am able to ping the Domain Controller from the Vista machine

I need a reliable way of making the Windows Firewall on a Vista
machine [ and of secondary importance, on an XP SP2 machine too ] to
switch between using the 2 Firewall profiles Domain & Standard.