I Will try........ to delete my internal sound card.
However I plugged in a spare USB module and got same error.
Even further .......... I purchased a new USB sound device.... and cables.... got same error.
Remember.......  I set RIG to NONE and the decode of sample files works.

It is only when I click MONITOR button that I get the error. 

My first indication of trouble.......
ALL OF A SUDDEN one day the green level bar showed no signal.
I've been using wsjt-x for years with same hardware.