SPDIF out of sync

[Brian_92gsr]

I've narrowed my audio out of sync problem down quite a bit. I'm using the onboard sound of my MSI KT3 Ultra, which has an optical output. The sync on most stuff is perfect when I output AC3 using SPDIF. But I've got a couple files that are just slightly off. But when I switch to output a stereo signal through the optical out it stays in sync. Only when I use the SPDIF output via optical does it have problems. And again, this is only in a very small percantage of the videos I've encoded. I've messed around with all kinds of interleave settings, including turning interleaving off. It almost seems like the actual file is fine and the problem lies with my computer or software. I've tested the file on other computers and it is fine, but only in stereo. I have no where else to test the SPDIF AC3 output.

[Brian_92gsr]

It would seem that it actually only loses sync when I seek to a different part of the file. I just watched a movie all the way through that I was having problems with, and it kept sync throughout the whole thing. I usually never seek to a different part of a video, I usually watch it from the beginning, but I'd still like to know what the problem is. Any would would be greatly appreciated.