Hi jmeade,
If I interpret your post correctly, the problem seems to occur on the DSM-520. Playing the audio from your laptop wired or wireless is fine.
If so, it may be possible that something internal to the DSM-520 as become corrupt such as a database, config profile, etc. It would be helpful if you could think back to when the problem started happening to determine if you possibly added extra media files that are perhaps causing a problem. Additionally, have you added/changed anything on your home that maybe causing some form of issue - wireless a/v receiver, new wifi-router, etc.
Cheers,