Connection Timeout with Airport Update

I've had a Macbook since July 2007 with a checkered history with wireless networks. Right now, I have Mac OS X 10.6.5 and, with my recent update, I downloaded AirPort Base Station Update 2010-001 5.5.1. I understand that Connection Timeout is a recurring problem with Macs, but I'm not sure if that's exactly what's going on. When I turn on my airport, it searches momentarily then says none of my networks were found, despite listing my desired network. When I click on that network (sometimes it asks for the password even though that's already in the keychain) it gives me that connection timeout message.

What's odd, though, is that is doesn't happen consistently, only when I'm a certain distance from my wireless router. If I'm in the same room as the router, or even the next room, I can connect just fine. If I'm more than 20 feet away from the thing, though I can't connect. I've had this problem before (with my parents' wireless network), but it was never so severe. Before I downloaded the new update, I never had a problem with my current network.

I've seen a lot of suggestions and the ones that I've understood enough to try don't work. Apple is no help becuase my warranty expired a few months ago, so it'll cost me $50 just to talk on the phone with them. Can anyone help me out, or even give me a hint about what to do?

Moved to correct forum.

Which Airport Base Station are you using? Encryption? Broadcasting the SSID? Have you tried changing channels?

Sorry about all the questions, but we need more info. It could just be a matter of weak signals as you move away from the base station, or it could be something else that's having an effect.

I don't know why this works for me but...

I got my MacBook Pro last July, and it has occasionally acted like it wasn't connected to a wireless network when the other computers were online with no issues. Like so many other people, it recognized the wireless network but it made me re-enter the password, then in less then 10 seconds I got a connection timeout. Once it fixed itself with a reboot (or shut-down, can't quite remember which). Then I figured out that all I had to do was unplug and re-plug my router. I am kind of a technological idiot as much as I hate to admit it, so I have NO idea why this works or why my Mac might have trouble when other machines aren't. I guess I should assume that most people who read this probably tried what I did so this post is probably pointless, but it worked for me!

Good luck to all those who have tried everything and still have the issue. It's not as if this fixed it permanently for me, but at least I don't have the problem all the time and fixing it for a while only takes me a few minutes.