I just got a new MacBook Pro laptop this week and the wireless networking stopped working no less than a day after I got it. The culprit? The 10.5.2 update.
Apparently this is a well known issue but Apple doesn’t make any mention of it in their knowledge base.
I figured since the laptop is brand new I would call Apple tech support to see what they had to say. They walking me through the typical stuff: reboot, remake your network settings, reset the hardware, upgrade my wifi router firmware, etc. Nothing seemed to help. Their final suggestion was to downgrade to 10.5.0. Unacceptable!
After a lot of experimentation, I figured out that the culprit in my case was the beacon interval on my WRT54G v6 wifi router. I had set it a long time ago to 1000ms, and the moment I changed it to 100ms (the default) it started working again. Change it back to 1000ms and its broken again. So strange.