I have been having this problem for the last few weeks. I have a 2.4 Alu. MB and recently while using an external monitor doing basic word processing/ web browsing my computer locks up and Bluetooth keeps getting removed from my system. The bluetooth keyboard was always in use during this lockup. I look under Sys. Prefs and and the icon is gone and I cannot use any Bluetooth Devices. It now says I don't have a Bluetooth Device on my computer under System Profiler. I saw on another thread and the solution was to reset the computer and hold down the power button for 10 seconds on the start up. This initially worked for me but now it's a no go. If anyone has any ideas, please let me know. I work 70 hours a week and really don't have time to visit the genius bar. Does this sound like a logic board dying? Thanks for the help guys.