Laptop  Acer Aspire v3.-572  (11 months old)
A week ago, my audio caused havoc.  From the audio came a piercing noise.  I did not know what caused it but I solved the problem by shutting off system sounds. My mail did not work, could not find the maps, messages etc.
 
A day later, in an effort to find a solution I switched from one language to another - English.  In connection with that system was rebooted and then Dolby  Digital Plus ver. 7.6.4.9  - must have been added in the same operation.  The changes were done by Windows update which took many hours.
Which is the Reliable souce to download Dolby Digital Plus?
 
I await your advice or comments.  JXJ40