Just noticed Lounge, it is working different there. Even a single upvote turns thread into green. Further, at right bottom corner, count of upvotes are shown. Both are missing here... Upvoted another thread of yours to confirm and still the same. You are getting points though, right?
Last night when I saw that hamster image (error page), I got the feeling that it has to be something about voting - all other pages were working fine. And in the morning I found those arrow with disabled downvote. It wasn't that bad with no votes in forums though, just saying. Disabling downvote is a good idea.