Constant Crashing after new FP install with current Firefox

FP 21.0.0.242   FF 46.0.1  Windows 7

Have reinstalled Flashplayer 3 times.  Constant looping error - flashes very quickly on screen - "FP plugin not responding" - Even if I am quick enough, clicking "stop plugin" does nothing.  I must uninstall FP to even use Firefox and/or kill both programs quickly in Task Manager.  I have now set FF for FP to "Ask to Activate" in Firefox, which temporarily enables me to use Firefox.  No matter what website that asks to activate FP,  the moment I allow FP to run, it starts the looping error and crashes FF.  As a last resort, am downloading FP 21.0.0 213 archive zip, but have a feeling that will not help and not sure where to move it to use it.  (have unzipped it)  Please help and thank you in advance.