After booting correctly, why at some point would function keys get remapped in Macbook Air? I have a mid-2011 Macbook Air. Sometime in the recent past, the Function key row (which I used for volume control, brightness control, keyboard backlight control, etc) has stopped working. 

By stopped working, I mean it seems like those keys have been remapped. For example, the "increase volume" function key shows the widget screen (with the clock, calculator, etc). Another function key shows the app dashboard.

I fiddled around with all the available keyboard settings in "System Preferences" but got nowhere.

Once, after a reboot, the function key functionality was reinstated, but all too briefly. After a few hours, the errant behavior has resumed.

Any pointers or ideas?
Without knowing what programs you have installed that could be doing that:
Like some keyboard remapper...


Log in as different user to make sure there is not something in you profile preferences


or


Start in Safe mode to exclude other applications. 


Then start applications one by one to find out who is doing it.

Also check this setting in System preference keyboard: