Whenever I import a longer clip (entire movie or TV episode) and cut out a scene that isn't in the very beginning, the sound is lagged in an unexpected way. It seems to "drift" over time, so that it fits perfectly in the beginning of the movie, but is horribly out of sync toward the end, and smoothly transitions to this throughout the movie.

I'm going to spare you the details of how I've cursed violently at this, even destroyed hardware and pulled my hair out of frustration. I've lost so many hours of productivity just trying to manually re-sync every damn clip.

OS: Windows 8. It was the same thing on Windows 7. All official stable patches. On multiple computers. None of them have any weird/exotic changes whatsoever. In fact, they are very clean and well maintained. This has happened in both CS 6 and CC of Premiere Pro.

Short clips seem to always work. It COULD have something to do with the .avi format specifically, but I don't know.

Very important: The clips that "audio drift" in Premiere Pro work flawlessly in all my media players. I can watch them perfectly in Media Player Classic, VLC, etc. Only when inside Pr, either as preview or as an exported file, do they have desynced audio in this manner. It's 100% verified that this only happens in Pr. In fact, even Windows Live Movie Maker seems to not be affected by this "drift".

Please help.