We have been using Virtual PCs to host a separate development environment. Some of the team members have been having sporadic network issues with SourceSafe on the Virtual PCs. They were unable to get all of the projects involved down to the Virtual PC without getting a “Network Not Found” error. Eventually they would get all the files, but it was clearly not the best situation.
The Virtual PC image was sysprepped before distributing it, to avoid network problems. Unfortunately, that is not completely the case. Sysprep does reset the MAC address on the Virtual PC, but it apparently happens when sysprep runs, not when the user is re-setting up the PC. After distributing the image, the subsequent users still had the same MAC address. This was causing network problems when more than one person were using the Virtual PCs at the same time. The problem manifested itself mostly with SourceSafe, especially when there was a large change and multiple users were getting all the latest files at the same time.
At least the solution was simple once we realized that the MAC address was the issue (thanks to an astute network admin who had noticed some problems with a particular MAC address on one of the switches). In the .vpc file (it's XML), there is an entry for ethernet address. It contains the MAC address the Virtual PC uses. If you remove the data from the tag, leaving the empty tags, Virtual PC will auto-generate a new MAC address the next time it starts up. Since that change the “Network not Found” error has disappeared.