Hitchy playback in QT renders

Hi All,

Did some searches and couldn't find anything, so hope this isn't a repost. I'm on AE CS3 and experienced something again today that has me flummoxed. When I render out my motion graphic (in this case a one minute piece panning and spinning around some photos), I'm seeing little hitches or slight jumps in the playback -it's not constant, but intermittent, but always in the same areas/times when it happens. I usually render out PhotoJpeg at 100%.

When I ram preview these in AE, they are fine. The whole project frame rate was build and created at 30fps and output to QT as such. I'm on an 8 core MacPro with 8GB of RAM. I went in and double checked the keyframe graph and the movement is all linear, and perfect.

I can't think of what else could cause this, but when clients need QT movies for the web, or presentation, this always seems to happen.

Thanks for any advice!
~Chris