House repairs provide a lot of good software analogies. Once during a big rain storm, our window started leaking. It was a newly installed window, and it had never leaked before. Well, obviously a leaky window can become a huge problem if left unfixed. So, I went out sometime later, sprayed the window with the hose to try to get an idea of where the leak is (I was not, and still am not, a house repair expert), and to my great frustration - the window did not leak. Of course I wanted to reproduce the problem, narrow it down to the exact cause, and then make a quick fix - just like I would in a software project. I didn't want to rebuild the whole thing.
So, here is a "critical feature bug" (the leaky window), which occurred in "production" (during the actual rainstorm), but I cannot reproduce in my "development environment" (sunny day with my spraying the window with a hose). It was a non-reproducible bug. However, I couldn't just ignore it or look the other way, I needed to ensure that it didn't happen again (given that it's my house, I need to take "ownership" of the "project"). It's the kind of thing that drives a software project mad.
In this case, I just 'blindly" resealed things - checked the siding, exterior frame, interior, etc... And the window never leaked since. If it does end up leaking again, then I'll probably need to call an expert, much like how some doomed software projects sometimes call in a star consultant to troubleshoot their obscure bugs.