The measures should be a carbon copy every time.
The only time I find the measures different is when my computer decides it wants to perform some other task during the sweep. The result is an interference in the sound of the sweep. It isn't smooth and continuous, as if it had gone and performed another task and then came back to the sweep. I have come to recognize this problem and whenever I hear it I simply cancel the measure and try again.
This only happens on my old challenged computer. My fast computer doesn't have this problem.
Do you think this is your problem?
brucek