When I was contracting work form the cable company a while back I noticed that most people with wireless routers did not have them encrypted. They would tell me stories like, "It keeps booting me every 10 minutes or so". Another thing some would say, "I can't get on my wireless anymore it keeps asking for a password". Then they would tell me, "They never set a password and don't understand why it would be asking for one". I would have to tell them how they were most likely hacked by a neighbor or someone close by and they set up the password.
Well on some routers there is a security feature that will boot any person that is not logged in with an encryption key code. This would be the reason some people kept getting booted every ten minutes. But the few that told me about the new password being set had a whole different problem all together. After telling them a neighbor did it, confused them even more. They were baffled as to how they could do something like that. I explained to them how the modem comes with default settings.