The first thing I would make sure is that you are measuring the voltage with a good DMM and that you are measuring the voltage between the channel and DGND with nothing connected to any port. It is possible that you are pulling to many amps from the digital lines. Next, try inserting the DAQ device into another computer, to make sure the problem is not related to the computers PCI bus or power supply. If this fails as well, I would suggest creating a service request on-line and calling National Instruments.
I hope this helps out.
Joshua
