Here are the things I've tried to fix this issue so far:
- Tried all available Nvidia driver sets going back to 67.03, which is the first driverset to fully support the Geforce 6 series of cards. Driver cleaner was used to ensure total removal of preexisting drivers.
- Tried all available sound card drivers.
- Tried disabling all unnecessary background tasks.
- Tried changing the hardware acceleration levels in the sounds and audio properties.
Unfortunately, none of that has resolved the problem (even though all of them were long shots). The problem is most likely a buffering issue as you describe, but it seems a bit irritating that it's struggling with something like this. Particularly when all other video formats play without issues.