Belkin wi-fi problem!

I bought a Belkin N1 wireless basestation about six months ago and I was really pleased with the range and speed I get in the places in my flat where I usually want to connect to the net. Not any more. In a couple of places the network appears to have vanished. I haven't changed the settings, I have rebooted the N1. There are a fair few networks aroundabouts, but not so many as I can detect when I'm in the office, and I have no problems connecting there (different basestation though). Help!