Harold,
There were some similar issues reported with the 4350 caused by calibration problems. Here is a link describing the issue and a fix fo it:
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/3e912aa203b8033e86256ae3005086a3?OpenDocument
If you are still having trouble, the 4350 hardware is handled by the DAQ driver for recognition. Try reinstalling DAQ or updating to the latest DAQ driver:
http://digital.ni.com/softlib.nsf/webcategories/85256410006C055586256BBB002C128D?opendocument
Regards,
Chris