Using Firefox, Windows 10, Flash Player goes black and crashes

Using Firefox and Windows 10, the flash player frequently does this:

     1.  The player plays fine for 20 seconds to a couple of minutes

     2.  The entire screen goes Black (with some shifting patterns, variations to dark green) while the audio continues playing.    

     3.  After 15 - 20 seconds the audio stops.

     4.  I cannot close Firefox or get back to a normal screen even with alt-F4, alt-Tab, or anything else.  The only option is to hard reset.

     5.  This ONLY happens while using Flash.