Frequent crashes when exporting audio from mov

Hey, all. I do a lot of post audio work and must first convert my mov files to DV AVI. Video conversions work nearly 100% of the time, but I frequently get crashes when using the Sound to Wav export (better to have a separate audio reference track to accompany the video). This has been happening forever, but I just did a clean install of XP Pro, SP3, installed the latest QT and authorized with my Pro license, and still get a crash. I've never been able to detect a pattern related to particular types of movies, and it often happens even when all default settings are unchanged. Any ideas as to what would cause this? Thanks.