Can those responding note if the have TL4+ rights or not. The reason being that many may not be aware that some users can mark a solution as solved even if they are not the OP of the topic. So they may read this and think that we are marking our own solutions as solved and have this problem. In fact the problem is that the solved button is on every post for us and thus easy to fat finger.
As noted later this is configurable but set to TL4 as a default.