What is it really you have a problem with?
The fact that these questions pop up as unanswered while they obviously are, so they clutter your search for new questions to answer?
Because really the signal to noise ratio isn't that terrible, especially since I believe most of these questions will be fairly old, so it's not a trend or growing problem.
Changing the status of these questions however, will have no influence on their usefulness. If it's answered and someone stumbles on our site with the same problem, the answer will also solve his problem. Regardless of the amount of upvotes or accepted answers.
I do agree it would be nice to filter these questions, to be able to find questions I can answer and/or that are worth trying to effort without having my results cluttered with false positives.
In response to your first comment: it would be better to give you a view or app that helps you find questions that are worth answering, rather than changing some of the fundamental elements of the site.
The only possible solution I could think off would be to allow mods to edit questions that are older than n-months and have x-answers with y-upvotes (you fill in the blanks). Though I really think we shouldn't mess with voting/accepting, as we have bounties and other elements to encourage this behavior
