Matt, thanks for your reply...
To answer your questions:
1) Labview version....first installed 8.0 fresh and then upgraded to 8.0.1
2) The DAQ assistant has behaved this way...though sometimes for no apparent reason it works perfectly
3) DAQMx version is 8.6 (installed fresh as well)
4), 5) & 6) I have not tried these....
To make sure that the problem is not hardware related (bad memory for example), I will be installing Labview on a new computer (windows XP pro) next week.
Please let me know if there are any steps to the installation that I should follow.
My plan is to install the following (in that order)
Labview 8.0
DAQmx 8.6
NI-VISA (latest version)
(other drivers...)
install the 8.0.1 upgrade