Brian,
To go along with the drawing Ian provided on 9/28/07, I'm attaching a sample tap file that demonstrates the failure.
It's a sine wave that shows how CV drops out when angles are in a [CCW] direction.
Running at 70 ipm you see the speed moving right along during the first half of the wave, chord angles are [CW] and CV is working.
Now in the second half of the wave the chord angles are [CCW] and it slows way down, CV has dropped out.
In Config/General Logic Config:
CV Dist Tolerance = 0.01
Stop CV on angles > 35 Degrees
Hope this will be useful to you.
Regards,
Tom