I was working on this system this morning when my BT mouse stopped responding. I went to check settings>Bluetooth and Other Devices (the windows store/Metro app) and found the BT option missing. Then I went to services and found all BT-related services to be disabled, so I started them. Finally, I opened device manager and saw a curious thing; the mainboard BT adapter disappeared approximately every 500ms and reappeared 500ms later. I tried rebooting and reinstalling the BT driver (Intel Wireless Bluetooth) but nothing helped, although it reinstalled cleanly.
Additional info; about 1/3 the time the BT driver icon has a triangle with an exclamation point on it when it reappears. Also, the hardware tab under device properties for the BT adapter is completely blank.