This was using the latest version (listed as 8.1.0f1 in MAX->software list).
To give a little history incase it helps.
First off I installed the latest Traditional NiDaq.
Wrote a small piece of software targeted for the PCI 6534 using the ActiveX controls in C-Sharp.
Decided to have a look at NiDaqmx for the same tool, installe dthe latest version and came across the problem originally stated.
Unistalled an ni software (both Traditional NiDaq and NiDaqmx)
Installed latest NiDaqmx and the problem persisted.
Not sure if this helps but it can't hurt.
Chris