Media is out of sync only in FCP

I've been freelancing at a Post house occasionally and lately, on the machine I've been using, almost all the media we take in is out of sync.

As far as I can tell, the audio is actually fine and the video jumps at some point, causing it to go out sync. So fortunately, it's not drifting, and once I figure out the length of the delay, it's easy for me to re-sync, but it's still a problem.

We've had all different kinds of media, captured from DV decks, ripped from DVDs, just taken in as quicktimes, etc... and they all seem fine when you look at them. But it's only when they are imported into FCP that this happens. It happens in both the viewer and the timeline.

I've recommended a clean re-install, but every time I go back, they haven't done it yet. Is there another way to fix this problem?

I'm not in front of the machine right now so I'm unsure of the specs, but it's a pretty standard G5 FCP machine.