I know I (and others) have complained about this before, but it doesn't seem to be that widespread of a problem (or at least enough to urge others to complain).
The issue I have is that whenever a post contains an embedded video, the comments section loses all the nice functionality (mainly that I can't mark comments as read, or automatically scroll through). This wouldn't bother me so much, except that if someone replies to an earlier post, I have NO idea where that post is, since everything is still highlighted for me (unless I browse away, and then back).
I figured I would poll people to see if this is a browser specific thing, or if it is something else that only affects a subset of users (such as operating system, but that would have made this poll too complex, though if this poll isn't conclusive, then perhaps I will do another one with OS).
I currently use IE8 on Vista, but I also had problems with IE7 on Vista.