Aporte original por: martin.pfister1 ,
There is only one solution to me that is helpful indeed. Shut down computer manually. Wait 10 seconds. Start again and when you hear the first sound/signal, press cmd/alt/P/R all at the same time until you hear the second start sound. Then release the keys. At the beginning it worked every time. Later (now) i have to do it up to 4 times. But: it works. Good luck folks!