I did not see any recent entries for this and NI struggled with a quick solution, so I am putting in a tip. On a new LV7.1 installation on an XP Pro system, I could not access any Trad Daq VI's. I would receive an "initialization routine failed" for LVDAQ.DLL. Using the Administrator account and my user account (also with admin rights) I installed, re-installed, and upgraded NIDAQ to 7.4.1 multiple times. The solution was to enter regedit (backup your registry!) and select HKLM/Software/National Instruments. Select Edit/Permissions/<user account having trouble> and allow "Full Control" for the individual user account. Even though full control was enabled for Administrators as a group, and my account is an admin, full control was not enanbled on my account by default. After reboot, it works fine.
PS: Thanks Andrew!