It might help your anxiety a bit if you were to get that door fixed, get one of those chain things, they are easy to install and cheap too. If you own the place than I would say get a deadbolt installed. Or if you rent, get you landlord to either do it or get permission to do it. but as to the locked door flying open, sounds as if the knob isn't installed properly (had that once) the problem could be the bolt part doesn't extend far enough into the slot for it in the door frame. (I don't know all the proper terms for door knob parts so I hope I'm making sense) I know that doing all of this would be a bother, and won't get your computer back, but think of it this way, a good lock is cheaper than a computer & installing it is easier than replacing all your stuff. Good luck.