I think when the new aluminium Apple Wireless Keyboard batteries die, it corrupts the Bluetooth preference file. My batteries ran out, I changed them, but could not pair – the pairing pass key dialogue did not even come up!
BUT the keyboard worked at login, when I had to input my password, but once my user desktop appeared, it stopped working. I assume the root level OS (ie before user loging) uses a different preference file of something.
I deleted the bluetooth plist thing, restarted, fixed permissions, etc, and it worked!
How I discovered this, was that I noticed that I could not access the Bluetooth preference file, in the Bluetooth pulldown menu – I got the spinning rainbow disk!
Apple needs to get this sorted. The bluetooth preference file need to be robust enough to deal with a run down battery.
PS Tried the Airport interference thing, but that had not effect!
Aplle nee