These both seem to be sporadic right now, but I'll try to see if there are conditions in which they can be consistently reproduced.
The go to first new post is intermittently taking me several pages back into threads I've read all of. It's usually the same post in that thread every time it happens on a particular thread, and they're usually posts between 11 p.m. and midnight EST last night. It's happening in Opera and FireFox, so I don't think it's something on my end.
Quoted replies are also randomly stripping an open quote tag from a chain of two or more, but not stripping the matching close tag. And I'm not talking ridiculous quote trees of six or twelve people or whatever. Just two or three. At first I thought I was inexplicably drunk and mis-editing quotes, but it's happened three or four times, including quotes I didn't edit down, and I've seen similarly broken quoting in two other people's posts today.