Hello and thanks for the reply
I don't think that it is the problem. Every movie I insert into the drive has no sound. To ensure this I have also changed the settings in each player separetely from Dolby Surround, DTS, to other custom settings but without result. If I proceed to the format procedure the sound from will be ok for a time. But I can't go into this cause 1) I have many data to backup and 2) After a certain time the problem will reappear as I have already seen in a previous format for the same reason. I am convinced that windows media player has caused this but every effort to fix it (uninstall reinstall 10,11 media 9 codecs) has led to failure. However I appreciate very much your kind support.