I'm wondering if you can put the HDTV into the DMZ of the router.
I won't discuss how to do that since it's a little advanced. I'm also declining to discuss why I think that may help. It's something that helped a similar issue.
I have a HP N40L MicroServer, which rarely gets shut down, that I use to share video content around the house, with no problems on anything else. But with SmartHub, it worked fine the first day, but then the File Manager type window started hanging with "Loading..." message on the top left of the screen. At this point I had to turn the TV off and back on again to continue using the TV.
If I reboot the MicroServer, it again works for the first day, but not after that. A bit annoying having to reboot my server every so many hours just to get SmartHub to work.
I have tried Samsung AllShare as well as PS3MediaServer with the same problem.
All of my other devices work fine this way.