It would help to know if the HDTV is connected wirelessly/wired, which UVERSE device you have (make/model).
UVERSE is known for having issues with hardware/media device compatibility.
Our new 50 inch Vizio LCD Smart TV works fine until the smart part is connected to the internet, ATT uVerse
We've tried 4 Vizio TVs and the same thing happens each time. ATT blames Vizio and Vizio blames ATT.