Hello, thanks, it is a good idea ...
I removed the power widget on the home page and disabled widget locker.
I restarted my phone. Weirdly i had to insist to restart the phone.
When pushing power button, after 3 seconds, the lower buttons were blinking
but it didn't start, and then keeping power button 3 ou 5 seconds longer the phone restarted
That is not the first time i noticed that the phone doesn't start or stop normally ...
At restart, i didn't see 100 % "bluetooth on" in betterbatterystats.
It looks like problem is solved ...
I will let the phone like that for a moment and put again the power widget on home page to see if i get the error back.
And then activate back widget locker.