At about 6:30 last night, we again lost partial power in our apartment building. That happened another time, about a month ago; that's when we found out our building's hooked up to two power feeds.
We know more now: turns out (according to the electrician who showed up about 8:45 last night) that one feed is connected to circuit breakers, and the other, the one that went out, is connected to fuses. Fuses that he said are too small to handle too much power use.
Crap. I may have been the one who was using too much. I think I should post an apology to my neighbors: put up a note in the entryway, that kind of thing. And also ask our owners if those fuses (fuses, still!) can be replaced with some with more capacity, because I don't want to worry about using the computer and the microwave simultaneously. I don't think I should have to worry about that, either.