Hi all, I have an issue with an iMac 27". It has a Mac aluminium keyboard connected to it via USB. There are occasions where the keyboard just doesn't communicate with the Mac or has no power. The only solution I have right now is to restart the Mac, but the keyboard is still not always detected and communicating with the Mac after various restart attempts. I have also tried the following: 1) Different USB ports on the Mac, no difference. 2) Tried another keyboard of the same type, no difference. 3) Tried the original problematic keyboard on another iMac, it works perfectly! I keep thinking the USB ports on the problematic iMac are the culprits but it works fine with other USB devices like the Apple mouse. I can only think the OS is somehow tripping. It is a Mac OS X Mountain Lion. the iMac was provided to us only some months ago so it's practically new. Any help from anyone who's had these mysterious occurrences? Thanks!