FYI, I got this from the folks who make QT Edit. Seems to answer the question.
QuickTime timecode tracks have an optional flag that can be set that limits the timecode to fit within a 24 hour clock. It sounds like that flag is set on your file. QT Edit can switch off this flag, which should allow you to set the timecode correctly either in QT Edit or FCP 7.
Regards,
Jon Chappell.
CEO, Digital Rebellion LLC.