<<<That's normally a PAL-NTSC issue. Check the settings. >>>
If it's not, you may be suffering from FireWire-itis.
No, FireWire hubs don't work--at least not for video. Video is going too fast and it's too brittle. One false move and it's dropped frame time. Video can't go back later and correct an error.
It can be said you shouldn't be connecting the deck and the drives to the same FireWire port. That has been known to cause problems.
Save out the show as a self-contained QuickTime movie and park it on the internal drive. Disconnect everything but the deck, load and play the show that way.
If you haven't cured it some other way by now.
Koz