Vertical cursor line exhibiting random movement in Sonar 3

I don't know what the vertical cursor is called, but it is the line that moves and shows where you are in the wave file. The problem is it doesn't move smoothly across the wave file, but randomly jerks from one place to the next.  The playback isn't effected, but the cursor isn't working right.  How do you fix this?
thanks,
wadrum

Sonar 3 or Sonar X3? It really makes a difference.