Hi Iflash,
This error will sometimes occur during debugging of a data acquisition program. What happens is that when you start an operation and then terminate the program prematurely using the Abort button the process could still be running on the DAQ board.
The best way to avoid this is to reset the board. There are several ways to do this. The easiest is to run the Device Reset VI in LabVIEW. You will just need to wire up the device number and run the VI. Another option is to go into Measurement & Automation Explorer (MAX) and run the test panels on the device. It will error the first time but if you close the test panel and run it again it should be fine. Finally, in MAX 3.0, there should be a Reset button that you can access from the Devices and I
nterfaces >> DAQmx devices.
Anyway, hope that helps. Have a good day.
Ron