Today I had to do some work on an old VB6 system, a development environment I do not have on my Vista laptop.
So I copied a Virtual PC image I had with most of the tools I needed and ran it on one of our Virtual Servers. As this VPC needed to run at the same time as the VPC I copied it from, I ran NewSid to change the SID and the PC names.
All seemed good until I tried to use the network, both within our LAN and the Internet it was very intermittent, but I saw no errors.
To cut a long story short the problem was I had two VPC images with the same MAC address. Once I stopped the new VPC, changed the MAC address and restarted it all was fine.
So the Technical Tip is – if you copy a VPC image you need to run NewSID and manually alter the MAC address to avoid network clashes