I have the habit of everytime someone answers/comment one of my questions, i go trhu their list of questions and see if I can answer/contribute to any of the unanswered ones.
A few days ago I started to have some trouble on windows and the users answering windows questions have lots of answers and reputation, but zero questions.
I thought everyone had to ask questions to even start to be able to reply... Or do they delete their old questions for some reason?