Mac WiFi connection timeout error

I have just spent around three hours trying to get my MacBook to connect to my home WiFi network. It will not automatically connect when it starts up, so I click the WiFi icon and let it scan for networks. It finds it, I select it, and an error message comes up saying there is a connection timeout error.

The thing is, the MacBook has been happily connecting to this WiFi network for months. Nothing has changed, except now the MacBook has decided it doesn't like the network.

A search for Mac connection timeout errors at Google will produce lots of links and it appears to be a common problem with many threads on support forums, including Apple's. It happens with new Macs running OS X Lion and links go back several years to old Macs running Leopard or Snow Leopard.

There are numerous fixes and what this means is that no-one has a clue and it is something really obscure. A fix that works for one person fails for another, which is very odd.

I'm running OS X Lion and wondered whether it was a software problem, so I booted up from a USB drive running Snow Leopard - a copy of the internal drive I made ages ago. It works fine, or it did the last time I tried it, but now it can't connect to the WiFi.

Removing all the WiFi networks from Networks in System Preferences didn't work, starting with Command+Option+P+R didn't work, deleting all the networks and manually adding it didn't work, getting new DCHP leases didn't work.

Oh, I forgot to mention, I have an iPhone, iPad, Windows PC, and an Android smartphone, which all connect OK.

At last I'm back online and connected to my WiFi, so what worked? I think this has something to do with the wireless router. Switching off and switching on allowed me to connect. Mind you, I had to do it four or five times before the Mac would connect, then bang, straight in no problems. That's weird.

I wonder if this is a channel problem. The router doesn't boot up exactly the same way each time. It is (supposed to be) a clever one that scans the area and attempts to find the best settings and when I couldn't connect it had started on channel 11. Now I'm back online it is using channel 1.

Now this could be coincidence and perhaps I would have connected if I'd changed my socks to a blue pair, but it makes me wonder. It is something I need to monitor. It is strange that every other wireless device in the house works fine on channel 11 though.