It seems to be that the nidaq version that you have in your computer is corrupted, or there is something weird in the installation procedure. I will suggest you to uninstall everything and reinstall everything.
The steps I would recommend you to do are these:
1.- Uninstall the nidaq driver that you have by going to Control Panel>>Add/Remove Programs.
2.- Remove the board from the Device Manger.If there is another NI board which is in your system, remove it, too.
3.- Turn off the computer, and take off your board.
4.- Install the nidaq driver again (either nidaq 6.9.1 or nidaq 6.9.2), you can download it in the following FTP site: ftp://ftp.ni.com/support/daq/pc/ni-daq/. Make sure you also download the supporting file for your LV Version 5.1. The install.t
xt file describes the instructions to install the driver.
5.- Follow the instructions to install the board that are in the following link: http://www.ni.com/support/install/
Hope these steps help you solve your issue.
Aguila