So there's a message board bug that I'm aware of. I'm sure it's known, and it's probably "on the list", but I figured I'd mention it anyways :)
I typically browse in 2 or 3 tabs. When I'm in a tab and I start to post and think better of it (probably something I should do more often), I then hit cancel.
The bug is that cancel doesn't go back to that thread - it goes back to the most recently viewed thread. So, for example, consider this sequence of events (in order)
Tab 1: Go to thread A.
Tab 2: Go to thread B.
Tab 1: Start to post in thread A.
Tab 1: Cancel. Goes back to thread B.
I'm guessing this is because something's stored in a single cookie or session variable, and it uses that cookie/session variable to see where it should go, rather than having a thread ID somewhere on the page that gets posted along with the cancel.
But I'm just guessing :)