Every once in a while there is a thread with 0 replies that has been marked as "Solved":
http://www.daniweb.com/software-development/cpp/threads/398278
When you sort by "Unanswered", I don't think these threads should be displayed (they currently are: http://www.daniweb.com/software-development/cpp/unanswered/list/8). Going through "unanswered" threads is surely in an attempt to answer some, and you most likely won't answer a solved thread.
David