Using Sonar X3e , suddenly the tracker line ... that vertical line that follows the track's timeline as it  plays or records ... in playback is jumping every beat  skipping to the next beat.  I say "suddenly" as I don't recall having made any settings changes that would cause this. Normally the tracker line moves smoothly throughout the timeline.    Any thought as to what is happening?  

Press Pause, you accidentally turned it on. (pressing again turns it off).

Thanks czyky.  I need to find Scroll Lock but for now ... all is well on this earth!  I shut down X3e for an hour or so.  Moments ago I re-opened it.  The problem was gone.  

I said scroll lock, should have said pause. If you can see the pause, try it while you're in playback. You'll see the behavior you described toggle on and off.
 
FYI, scroll lock toggles how sonar tracks the now time if it goes past the edge of the frame.

Again my thanks to you! When I realized it was the "Pause"/"Break" key on the computer's keyboard and not the pause button on Sonar's Transport section, I was able to replicate the  "fault".