There shouldn't be an over-ride. Usually either swapping out the HDMI cable or resetting/refreshing or updating the cable/sat box will allow you to get past this symptom.
Try to see if your box can be reset or refreshed (they can usually do this while you're on the phone with their customer service), since that would cost nothing. Then, try the cable swap to see if that helps.
What resolution is your cable/sat sending to the TV?
Keep me posted.
I can't tell if this is the same as the other blank screen problems reported in this forum. My screen goes blank (with sound OK) only on HD channels and seemingly when bright images are flashed on the screen (think Apple commercials). Occasionally the blank screen evolve to a complete signal loss. It does come back after 5 - 10 seconds but it is very annoying. Is there a brightness override that's kicking in and, if so, how do I disable it?