Out of Sync but Not...

I capture uncompressed video through a BlackMagic video decklink card. The files get quite big (100 gigs plus sometimes). I have one particular video that I captured that is giving me problems. When I watch the clip in Premiere Pro, it's fine, no errors. When I watch the same exact clip in Windows Media Player or Sorrenson Squeeze, the audio and video of the clip get out of sync at about the 75% mark. It's the same point every time in both of those players so it's not an issue whether my computer can handle the large clip or not. I've exported the clip and watched it... when it's in Premiere it's fine and in other players it gets out of sync. Is my clip actually out of sync or is it some other problem? Advice/explanations would be welcome