My bluetooth just disappeared. I am using a usb dongle; the internal bluetooth module went a while ago. Now bluetooth does not appear in system report and system prefs. I have been using an apple wireless keyboard and trackpad as well as bt headphones. Is it likely the dongle or system board? An old bt 2.0 dongle also doesn't appear when swapped in. It happens when booting from two system drives. USB is working. Weird that the BT prefs are gone. Is it normal that they would simply not load if the system didn't detect bt hardware on boot up? If this is so, and assuming not both of my bt dongles are busted, what other hardware (presumably on the original and still installed module) would be required for BT? Any ideas appreciated.