I just bought a DSM-750 for christmas. I have it setup in media lounge mode, not as an extender. It will show all the media from all my computer running either vista home premium or windows 7 ultimate but will not play any of it. I set up a D-link media server on one just to see if that would work and nothing. Again it will see all the media but will not play any of it. The screen just goes black.
The interesting part here is that I had it working fine the other day. Again it was not working after hours of trying to configure everything to work. I gave up for a while and when I came back to it hours later, it just worked. Now it is back to not working and as far as I know, nothing has changed with any of my computers or my network.
Router is a DIR-655 and the DSM-750 is running wireless if that makes any difference.