Could not load Network preference pane
The first sign was that Airport card monitor in the status bar showed no reception and, worse, says "Airport card not installed". If I then try to load the Network pref pane from System Preferences, I'm met with a message box telling me it can't be loaded.
The .prefpane file is present in /System/Library/PreferencePanes (and, for what it's worth, plutil /System/Library/PreferencePanes/Network.prefPane/Contents/Info.plist returns OK).
I've repaired disk permissions (both as normal and from the install disc).
I can still connect to the network, though, so it's not the end of the world.
What's next to check?
MacBookPro 15", Mac OS X (10.6.3)