i somehow ended up with a very short segment of my arrangement which would play back twice as the transport passed it.
you could see it visually and hear the stutter in the audio
to be clear,
the transport would play normally up to this point, then jump back and replay this segment (~1/4 second) and then continue on again...
kind of like a "wrinkle in time"
this was on an important set, so it freaked me out and i closed live and reverted to an earlier save. so, unfortunately i don't have the .als which shows this problem.
i believe that it was caused by moving warp markers on a clip