Mouse wheel stopped panning

Yesterday everything worked as it should.  Today, the mouse wheel does not pan, or do anything aside from zoom.

I've checked and re-applied the mouse settings, and restarted SWX (twice), but it still does not work.

How can I make it like it was (functional)?

FYI, I work on a Dell T3600 with an Evoluent VerticalMouse 4 (two months old).

SolidworksGeneral