Hi Jim,
Lol, this is precisely why i brought the question here to the pros. i have no idea what is causing that hair issue. it certainly is not normal. Time dictated i moved forward as the job was right at the finish line, but what I'm gathering from everyone's answers is that i may have caused other issues with my work around, like the lip sync on hdtvs.
I wonder is it something to do with the masks i use in After Effects. Could there be something that MPEG2 doesn't like in the feathered edges of the mask? Hair just happens to be in the area being affected. The footage was keyed out using keylight in AE brought across from PP by dynamic linking. There were a couple of other glitches that occurred on export like one frame of the interviewer having half their face disappear, rectified by going to the AE composition, activating a mask point on the offending frame and moving it a fraction.
If anyone has any suggestions as to why this is happening i'd love to hear it.
Sai