Ray,
Does this problem occur with all new MP4 video files created in PTE 9 ? Try to play projects (MP4) with different durations - 1 minute, 5 minutes, 10 minutes, 24 minutes.
Send me any sample video which has this problem with your TV. I will check on my TVs.
P.S. You can also try to create MP4 video with custom parameters - 1-pass bitrate (say 5000 kbps). Or try 48 KHz for audio instead of 44 Khz. Will it help?