Several users have reported an issue in which their function keys not working properly on their laptop computers. With relatively new computers, users have had various warning beeps or complete lack of function occur upon pressing any of the function keys.
Apple Discussions poster SPOB writes:
"I've had a MacBook for a couple months now and just recently i've been having a problem where when i try using any of the keys in the top row of the keyboard it just beeps and does nothing only the eject key works and the increase volume button opens dashboard."
This problem may have started after the latest Mac OS X update, or could be due to some faulty system setting that was inadvertently set. Additionally, in some applications, certain function keys are not supported, which will cause an error sound when users press them.
Things to Try
Toggle Keyboard layout While it is unlikely that a specific keyboard layout would change the function key mappings, users might try resetting the keyboard layout to "US" or other desired language. To do this, open the "International" system preferences and in the "Input Menu" tab uncheck all but the desired keyboard layout.
Toggle function key vs special features In the "Keyboard and Mouse" system preferences, uncheck the option to "Use all F1, F2, etc. keys as standard function keys." This option will prevent the volume or other "special" functions from working unless users also hold down the "Fn" key, and instead will give a system error sound if applications do not support the F-keys.
Reapply the latest OS update For users who have experienced this problem directly after an update, and for whom the previous fixes do not work, it is recommended to reapply the latest Mac OS X update by downloading the "Combo" update from Apple's website and applying it when booted in Safe Mode (hold shift during boot).
Reset PRAM It is possible some PRAM setting could cause input malfunction, so affected users might try to reset the computer's PRAM.