Got a similar problem but not quite. Everything stays in sync or is out of sync until you stop. If I play a section of my edit the sound is 2 frames early and stays that way until I stop and play again. Then it might be early or it might be in sync.
So far all playouts have been in sync but I don’t know if this is just luck.
I don’t know if this is a card fault or FCP? It is reasonable to expect correct A/V sync isn’t it? Has anyone tried Kona cards?
I am running:
Power PC G5 dual 2.7GHz
3GB RAM
FCP 5.0.4
Quicktime 7.0.4
OSX 10.4.5
Blackmagic Deck Link 5.4.2 (card supplied with multibridge SD)
3x500GB G-RAID FW 800
External B&B ref
DVCPRO50 PAL codec
Sven