As someone who doesn't like to shout, I have Caps Lock remapped to Control on all of my computers. A second control key is far more useful to a guy who spends most of his time in Terminal.app. This was set up in System Preferences under Keyboard and Modifier Keys.
My MacBook Air (MacBookAir3,2) keeps 'forgetting' this setting every couple of days and reverting to SHOUTY CAPS LOCK. I haven't yet pinpointed when it is reverting. It happens more frequently than me rebooting the Air but less frequently than me closing and opening the lid.
I don't have this problem on my MacBook Pro, Mac Mini or iMac. All four Macs are running Mac OS X 10.6.6.
I've searched the web but to no avail; I've never connected an external keyboard, mouse or trackpad.
Help me, StackExchange Users, you're my only hope.