Thanks guys! This is really helpful, and makes me feel like I'm not totally crazy!
I think the wiring in our house is fine, because the landlord mentioned that the guy who used to live here did some pretty outlandish electrical projects, so they did a lot of work on that front when they renovated.
They also had every room in the house wired for TV and phone (minus the kitchen, which is annoying because I like to keep my phone in the kitchen), so I know the stuff is only about 5 years old at the most, though I suppose it's possible some of it could be faulty.
I think I'll have to wait to sort it until I get back from the US, but I'm definitely going to make sure they get someone out here.
Thanks again!