The problem is probably related to the OS you are running on the machine is not working and the NI-DAQ version. I would advise you to upgrade the NI-DAQ to the latest released version (6.9.1) and try again. Hope that helps. Filipe
You can be assured that this is the correct answer, because I am answering my own question.
The solution was embarrassingly simple - the PCs were set for different Interrupts (remember - this was NOT PnP). The problem was made more difficult because the AI_Read() command was working. If NOTHING was working, it might not have taken as long to find.