hi mary,
this is 100% OK, because I guess you are working with interlaced material.
AVID maybe wont output the fields, so you will see only one field progressivly – but there are two fields, so your quicktime-file is really fine.
if you are bothering with quicktime, you can turn on the deinterlacing quicktime-output.
to do so you need to open your video within quicktime and turn cmd-j (on mac) on pc it might be ctrl-j.
then select video track, select your visual settings and check the deinterlace-checkbox.
right now you wont see the interlaced-artefacts anymore, and then save your quicktime-file.
NOTE: if you give this filme to someone else for broadcast for example, the deinterlacer needs to be off, otherwise there could be problems with your film.
cheers
danny