If I’m understanding the problem, I would try to narrow down where the problem is coming from. Did you play the clips in the standalone QT player? If it isn’t there, then AE is the problem. If AE is the problem, it could be a couple of thing, even the way that it is interpreting your footage. I’d make sure that your footage is brought in at the same rate, size, etc., as you exported it from Avid. If that’s OK, try rendering the project with the effect off.
That’s where I would start.
T