Hello,
Another troubleshooting step would be to turn off the PXI chassis, change the slots where the boards are located and take the measurements again.
You can contact the technical support department directly by choosing "Phone NI" and creating a service request over the web at
http://www.ni.com/ask. This way we will be able to help you troubleshoot and, if necessary, help you send your board for repair.
Regards,
Claudia Lorente
Applications Engineer
National Instruments
http://www.ni.com/ask