keeping post 4.3 update concerns listed here.
need more info.
are you rooted?
do you have a third party lock screen?
if you disable bluetooth, does this screen pop up still?
is it bluetooth devices or is it bluetooth tethering?
look in your bluetooth tab and what items do you have ticked?
does this happen anywhere or just at your home? or just at your job? or just in the car?
you have of course soft reset,, but did you also hold down the power button until the phone shut off on its own and restarts?
you are having difficulty not finding others on the internet with this issue because its possible its only local to your device...