We do not have any reports of similar behavior with this setup, but I willt ry to give some suggestion:
1) Run other applications to see if this is specific to the 435x software.
2) Run some of the 435x shipping examples to determine if the source is the NI-Driver or the specific code you are running:
C:\VXIpnp\WinNT\NI435x\examples
3) If the examples are causing the behavior also, unistall your current 435x driver and reinstall the latest version:
http://digital.ni.com/softlib.nsf/websearch/D395CD8CFCC9272E862569430075E527?opendocument
I hope these steps help in narrowing down the problem.
Best Regards,
Chris D