What revision of the FP-1600 do you have. You can determine this by looking at the back of the module. There is an assembly number 185690X-01 where the letter X is the revision. If your module is not a Revision E module, then I recommend contacting National Instruments support (www.ni.com/ask) to arrange for an upgrade of your module. If your module is revision E, then I would suggest you check the stability of the power supply going into the FP-1600. If the power supply drops below 11 Volts, it is possible to lock the FP-1600 up in certain cases.
Regards,
Aaron
LabVIEW Champion, CLA, CPI