Stuttering display problem

Hey,
 
I've run into a problem I cannot figure out a solution for...
 
I'm working on a new project that includes only 3 audio tracks and one instance of Superior Drummer 2.  My CPU Usage is displaying 5% and Disk Usage is 1%.
 
The problem I'm having is that when I go to increase (or decrease) the size of the tracks by dragging them in the Track Pane, the motion is not smooth.  It is stuttered.
 
I've gone back to earlier projects and found that it does not do this.
 
Superior Drummer is the most recent software I have installed on my DAW and I thought (and maybe still do) that it is the culprit.  However, I tried removing it from the project, but the same behavior exists.
 
Any ideas or suggestions?
 
Thanks.

I just love having these conversations with myself... 

Well it seems, it solved the problem only temporarily.  If I delete all of the WOV files and then open the project, it works fine.  However, if I close the project and re-open it again (without deleting any WOV files) the stuttering problem reappears.  Does anyone have an idea as to what might the problem here?  Thanks.