answer:It seems like you know what you’re up to re: your system preferences, but just to make sure: In System Preferences > Network, select “Airport” and check the box next to “Ask to join new networks.” This will prevent your computer from automatically joining unknown networks. Click “Advanced…” and you’ll see a list of all the networks your computer knows about. Go ahead and erase all the ones you don’t want to connect to automatically—including your neighbor’s signals—and (if all else fails) erase everything except for your home network. Your computer might be losing the signal for your home network, and then searching for the next available one. Then it will switch to that, because it can’t find the default network. If you follow the steps above, your computer will keep searching until it can find your home network again.