If you see an old question suddenly appear at the top of the list, it may be because it doesn't have a green "answered" checkmark, and the background "Community" task has pushed it up to the top.
You can do your part to stop this horror! If you see this happen to one of your questions, mark it as answered.
Just in case you need an arbitrary answer to accept:)
Though it may be useful to keep this exhortation showing up from time to time...
Seriously, I comes at a surprise to me that some folks are so friendly to write a comment saying "Thanks" or "It worked!" but don't click on the "accept" button... Are we too much conditioned by NNTP behaviour?
answered 23 Jul '10, 13:55