I have had a similar with a non-NI board myself. It turns out, the dlls were built for NT, but had a W9x equivalent. You may find that you have to dig deep into your VIs and either replace the one that is giving the problem, or even reconfigure the dll to call the correct version.
When you do platform specific development (even when you don't realize it's platform specific), you have to take this kind of thing into consideration.
Good luck, and let us know if you are still stuck.