That's a good thought. However, I don't think that's the problem here. As a certain bearded Jedi would say: I'm afraid the situation has become much more complicated.

I tried creating a new project in premiere and imported the m2v file there. The blockiness occured at the exact same time in the video.

I tried re-ripping the dvd to create a fresh m2v file and then loaded it into a new project in premiere, and the blockiness once again occured at the exact same time. Though as before it only occurs in premiere and not in while watching the source file.

It's so silly.

I'm thinking perhaps it could have something to do with the dvd, but then the blockiness would occur in the source file as well, wouldn't it? I'm so confused.