Hello,
This is a great question. The answer is to first uninstall NI-DAQ 7.1 using Add/Remove Programs. You may need to select the National Instruments category and choose Change. You will then be able to select NI-DAQ 7.1 and uninstall it.
Once you have successfully uninstalled NI-DAQ 7.1, reboot your computer. It is now safe to install NI-DAQ 6.7. If needed, you can download the older driver using the following link:
http://digital.ni.com/softlib.nsf/MainPage?ReadForm&node=132010_US
Make sure that you uninstall NI-DAQ 7.1 first. If you install two versions of NI-DAQ on top of each other, you will run into problems.
Let me know if you run into any difficulties.
Matthew C
Applications Engineer
National Instruments
