Hi Dan,
According to the LabVIEW help files, Error -1073807202 corresponds to VISA error code VI_ERROR_LIBRARY_NFOUND, which seems to indicate that VISA is having trouble finding or loading one of its code libraries.
I assume that you are using NI-VISA. If so, then you can check the VISA Interactive Control (VISAIC) to see if it detects your GPIB devices. If it doesn't, then try refreshing the view (View >> Refresh). You may want to try reinstalling VISA on the affected machines.
VISAIC is usually located under Start >> Programs >> National Instruments >> VISA. Alternatively, it can also be found under Start >> Programs >> VXIpnp, if you have NI-VXI installed.
I assume that each of these machines has the same version of LabVIEW and the same version of
NI-VISA, but please correct me, if I am wrong. If you need to download NI-VISA (to standarize on the same version or to download the latest version), then it is available on the National Instruments site in the Drivers and Updates Library. Go to the main Technical Support page (http://www.ni.com/support) and click the "Software Downloads" link. Then click the "Drivers and Updates" link.
I hope this has helped,
Dieter