Already stumped Apple on it - but I have the feeling someone may have the magic on what it is. MP on 10.6.8 using Bluetooth track pad and keys. I think this happens maybe 2-3 times a year. Lucky, Cinema Screen has option to pull up dialog to shut down - then press enter did restart. Now everything is fine. If it was HD issues, I would think nothing would function, so I'm not really satisfied it works now, and hope someone along the way found the glitch, so action can take place other that restart. Permissions were just done the other day-always an issue there. I removed batteries from trackpad, to doing any key board action. No help, the mouse can sit anywhere, but not make contact with item. Keyboard up/down can highlight files in Finder files, then SpaceBar can do QuickLook. Keys cannot access text document - any key pressed - simply flashes the screen. That's the deal couple hours ago. I had just moved a document by Bluetooth from Laptop to MP moments before. Went to close document on MP- No Access. MacBook Pro is 10.6.8 also. I shut it down just incase conflict being in same room. Thanks for the Magic.