Hewlett Packard was sent in for repair, came back with scratchy sound or crackles or no sound at all in some programs. I have checked for conflicts, have checked sound card settings, volume control etc. Have also checked for altered/deleted files with none found. Speakers are fine also. I've checked directx with no problems found there...but DID encounter a problem when testing direct sound, as no sound was heard. When I tested direct music, I could hear music at a very very low volume.

Any clues?

At times, a low volume of sound can be heard for a very short period of time following re boot.