Recently my brother has been experiencing problems connecting to our network via wi-fi. He has a 2006 MacBook running 10.5.8, with all updates. Most of the time when he tries to connect via wifi, airport will not be able to detect any wireless devices. On occasion, his airport will detect the router, but with a very weak signal (one bar, even when the computer is right next to the router). When he tries to connect, he gets a connection timeout. Similarly, he is unable to detect or connect to our neighbor's unprotected network. If he plugs into the router via ethernet, he can connect to the internet without any problems. The router is an Airport Extreme 802.11n. There are also two MacBook Pros, 2 HP laptops, an Xbox 360, and an Apple TV connected to this wireless router, and all perform without any trouble whatsoever. We've tried erasing all preferred networks, deleting .plist files, etc., with no success. Does anyone have any brilliant ideas? Might this be some type of hardware failure? Thanks in advance for any input!