Gary:

I suggest you uninstall WSJT-X.   Download a fresh copy from the Princeton site and install it taking the defaults.  Sounds as though the application has, somehow, been corrupted.

And after doing this, make sure the menus under RADIO and AUDIO tabs are set correctly for your radio and audio interface.  You may have to reduce the levels via the Windows Sound Setting menu. Typically the RX CODEC level should run about -10 dB or so.

73

Bob, K4TAX