I'm not sure why MAX is taking so long to respond when you try to expand Devices and Interfaces. I do have a couple of suggestions though. First you should be sure all of your drivers are up to date. For example you may want to upgrade to 488.2 version 2.3 and VISA version 3.3. From there, I would suggest testing this one board at a time. Does this happen with just one board in, or is it only when all three boards are in?
Emilie S. Applications Engineer National Instruments