I have an HP Spectre Ultrabook; 8G,128G SSD, W8.1, P/N E8G73UA#ABL, S/N 5CB34604T5, using microsoft Bluetooth mouse
on Jan 18, Windows Update elected to install KB2904440 deemed critical
Unfortunately, immediately after install and reboot, Bluetooth was disabled; Bluetooth slider option in the Network setting section became greyed out; activating airplane mode on and off did not reinstate Bluetooth.
I had to do a system restore to the point prior to the update AND that fixed the problem.
Because KB2904440 was the only change installed by Win Update and that occurred after the restore point I used, I am convinced that KB2904440 is at fault.
Anybody else encountered this ???