Switching windows between LabView and another program affects the readings from USB-6009

[May16]

I am running LabView 8.5.1 reading 4 RSE Voltage channels from a USB-6009 in a single operation every 250 ms.

Simultaneously I am running the control software (proprietary) of one of the instruments that provides two signals to the USB-6009. Whenever I switch windows between the two programs (LabView and the Propietary) the reading on one of the channels of the USB-6009 jumps to another value. Any idea what could be causing this erratic behaviour? If I connect the channel directly to a multimeter, instead of the USB-6009, this does not happen to the signal. 

The computer has two processors, none of them gets overloaded when I do the switching, as far as I can see in the task manager.

I appreciate any suggestions 🙂

[Burban]

You might want to switch firmware between DAQmx Base and DAQmx to reload the firmware on the USB DAQ.  The customer in this thread was seeing somewhat similar behavior and following the steps in this KnowledgeBase resolved his problem.