I am not sure what the latest version of software should be, but have you checked to see if any updates are available?
Nice suggestion but no joy. I went to "software updates" in Settings, asked it to check for updates and it said there were no updates.
The current software on our Roku 2 is version 4.1 build 1275.
Also, I should clarify that when watching the NBC news the audio is fine. Only the video is jerky or stuttering. I don't know what else to call it, but the video pauses for a fraction of a second every few seconds. This does not happen when watching Netflix. On Netflix, every few minutes the movie stops and the screen displays "Loading" for a few seconds, then the movie starts again.