Hello,
This appears to be an issue related to CMD.exe more than LabVIEW. When you say they this worked with 7.0 was it with the exact same command line passed to System Exec.vi?
A method to disable the check for a UNC path in CMD.exe is
described here. However, I must caution you that this suggestion involves editing the registry which should always be done with great care.
Scott Y
NI