When I bought my DSM-520 in January, it was mainly to watch Windows Media Center (DVR-MS) files on my TV.  This was Media Lounge 1.09 and Firmware 1.05.  Needless to say, the DVR-MS files did not play.  Well, they play, but with the audio screwed up.
After 7 hours on the phone with D-Link support (my lost weekend), I got a product specialist in California who immediately recognized the problem and said it was known and would be fixed in the next firmware update.  I was told to be patient, it would not be long, and that I would then love my DSM-520.
Well, 1.06 came and went and now 1.06.01 is here - no fix.  And D-Link still advertises DVR-MS support.
I have read other complaints about this in the forum.  I hope ECF is correct and it will be fixed in the next firmware update.  If not, PLEASE STOP advertising the DSM-520 as supporting the DVR-MS format so no one else will end up in the same boat.