That is actually what it is supposed to do, picture mute tells the tv to go to audio only mode. You could set the default stand position for audio, and the default speaker option for audio, to be the same as the video settings - then you would just get the screen going off. The BV10 doesn't have that facility.Do you have an audio system connected to the BV10?
BV7-40MK4BR,7-32,6-22,6-23,6-26,BSnd5,9000,BLab9,3,4000,2,BCom2,6000,Btalk1200,LC2s,Lutron