Does the same issue occurs while streaming videos from other Internet Video services too? Make sure that the latest firmware version is installed in the TV. You may download the latest version of the firmware using the following link.
Crackle is the only one I have had problems with so far. I have the latest firmware, 206. On Crackle the movie will start run for about 15 seconds and then reloads for another 15 seconds then does the same thing over again. I ran a couple of movies on popcorn flix and they ran with no problems. I ran a speed test and I get a ping of about 50 mps and download speed of .90mbp and upload speed of 1.05 mbps. I have att 2wire modem. Maybe the speed is to slow.