Incorrect voltages with USB-6008

[Mustard]

I am using a USB-6008 to measure a DC voltage of ~7.5V.  In differential mode, ports AI0/AI4 and AI1/AI5 work perfectly.  However, ports AI2/AI6 reports a value of about 1.4V when not connected to the DC voltage, 1.6V when connected and 0.9V when connected in reverse (i.e. - into AI2 and + into AI6).  If I then try to measure the DC voltage in RSE (i.e. AI2/GND and AI6/GND), I find that AI6/GND works perfectly while AI2/GND behaves similar to measuring in differential mode.  What could be causing this strange reading and how can I fix it?

All measurements are being made on the test panel and not through a vi (although I do have LabVIEW 8).  Operating system in WinXP and all drivers are current.

[Jarrod_B.]

Hi Mustard,

It sounds to me like there is something wrong with AI2 on your device.  Please go to the Technical Support page and use the Request Support option to contact us either by phone or e-mail.  The device may need to be sent in for repair/replacement.

Best regards,

[Mustard]

Thanks for the advice.  I am in the process of getting help through an NI rep.  However, I'd like to see if anyone else has any ideas.

I have done a little more investigating and have found the following:  With the USB-6008 plugged into my computer, I checked the output voltage of each AI compared to a GND port using a voltmeter.  The ports that appear to be working properly all report a voltage of about 1.4V as expected.  However, AI2 reports a voltage of about 0.9V and AI3 reports a voltage of about 0.6V.  Is there perhaps a setting I inadvertantly change that caused these two ports to drop in voltage?