I discovered this morning that it is possible for a human being to have a kernel panic, when I realized that it was impossible to turn on the Airport in my MacBook. Both the icon in the menu bar, and the UI in the Network preference pane, showed “Airport off” regardless of how often I said, “turn on, dammit.” More disturbingly, this happened without the ghost of an error log in the Console.

Here’s documentation on how I fixed it, for those of you who are Googling the same problem (and presumably have borrowed another computer in a mild state of panic):

1. Shut down your computer. Leave it off for a few minutes. If you want to be truly paranoid, remove the AC power and battery. Voltage weirdnesses can sometimes mess with the little minds of computer chips.
2. Hold down Command-Option-P-R, and wait for four startup chimes before proceeding. Yes, you are resetting the parameter RAM, the ancient cure-all of all problems Macintological. This three-finger salute is not nearly as useful as it used to be under Systems 7 through 9, but it can still be a magic wand sometimes.
3. Log in as a different user on your Mac. If this fixes the problem, then the problem is a corrupted setting somewhere in your primary user preferences.
4. Finally — and this is what fixed it for me — go to /Library/Preferences/SystemConfiguration, and drag the entire SystemConfiguration folder to your Desktop. (The /Library is the one at the top of your hard drive, not the one in your user folder just before Movies.) This blows out your entire saved network preferences, and apparently was where I had a corrupted setting.

If you make it as far as the last step, you’ll need to re-enter all of your wireless passwords… which is probably better than a dead wifi card making all those stored passwords moot.