Ok firstly other DLNA devices - Smart Phones, most have the DLNA capability, so get a friend over with theirs. Any Samsung smart phone will do, My old Omnia HD can.
Secondly I had the same problem but different reason, i was running both wireless and wired. TV to router wired and both to PC. I found that the LAN connection was disconnecting for some reason- havent bothered to figure it out yet. So it may have worked in reverse by disabling my wireless. Since I've been running wireless not issues so far. touch wood.
Thirdly if you for some reason running your media off an external usb drive this will cause a disconnect every 10 mins from the autosleep function in USB drives.
Lastly, After trying the various ideas of other people you may find the one mans solution is the ruination of anothers.
Simply put the changes previously made may be affecting the actual solution.
Hope this helps a little.