The TV has never streamed video from my pc without the "loading" screen. It came with a wireless dongle that worked as a "n" network adapter. My router is a "n" router, so I thought it would be fast enough to stream. When that didn't work smoothly, I ran an ethernet cable to it from downstairs and, though it stops and shows the "loading" screen, it now only shows it after about 10 seconds of video instead of every 5 seconds. To me, it seems as if the tv can not buffer enough video.
My blu-ray disk player also supports streaming video from a networked pc. It has a wireless connection to my lan. I tried it and it works flawlessly. There is a brief pause for "loading" and it plays the video continuously to the end. The pc and the network adapter are working fine and obviously supports video streaming. The TV supports this as well, but can not even do it with a wired connection. The issue, to me, appears to be the TV. I have installed all of the updates that the TV has indicated were available.
I guess, for now, I'll just use the blu-ray player. It works really well and upconverts the video. I saved your answers to help me when I get around to checking the tv.
Thank you for all of your help.