Audio Sync error in FCP 7
I have edited a movie and divided the movie into 8 parts so it can be easier for sound engineer for dubbing and putting background score...Now as they do their work in windows I converted the 8 parts(QT .mov format, 24 FPS, Apple Prores HQ, 48 Khz audio) into (.Avi, 24FPS, 48 khz Audio)..............Now when he gave me the New audio of 8 parts and when I am importing them into my FCP's Timeline where the old 8 parts are there then the new audio's size is slightly smaller...i.e The audio and video are not in sync....!!!!!!! When I somehow managed and brought them into sync. Now for giving the movie in print i have to export the audio files seperately too....So then I exported the new Audio from 'Export using Quicktime Conversion' Wave, 48 Khz, 16 bit...then again when i bring the wave audio back in timeline just for checking the sync...Then it also gets OUT OF SYNC!!!! I mean what possibly could be the error???
Once I brought the Audio into sync and after exporting the new synced audio and bringing them back in timeline, again it gets Out of sync................
Would like some help from experts regarding this...........
Thanks
Mac OS X (10.6.7)