I have an asrock AM2NF3 Vista board with win 7 . The sound just stopped there is a hiss as booting up finishes for a second or 2 .If I play a cd or audio file or a vdeo clip I get strangulated bursts of very distorted sound ,I can increase and decrease the volume level of this noise , I reinstalled the drivers for the device no difference where to from here .It is on board sound