Fences has detected that explorer was not closed properly...

I see there has been some history on this....

I have just returned home after two days away, during which time my PC was off, rarely - it probably hasn't been shut down for more than a reboot for a year or so.  And I'm getting that error - clicking to re-enable just causes more of the same.  Have purged, reinstalled Fences 3 from my account etc - no dice. 

Nothing has chanaged that I am aware of.  It's a personal machine, nothing beyond Malwarebytes out of the ordinary.  HELP!