1. Login into SL
  2. Move around
  3. Quit by clicking the X button on top-right
  4. Wait ... and wait ... and wait ... for the shutting down box to disappear (See attached screenshot)
_Sometimes_ Windows will even say "Application has stopped responding", but if you don't force close, SLV will, _eventually_ , close on its own.
Just need to be ... patient ... patient ... patient ...
Note : I've seen this behavior in 7.1.11 but it seems it's getting worse (with 7.1.11 Windows never complain about "Application has stopped responding", and the wait is not as long.)