I have had Fios since October '06, same day that I set up my S3. I check my cableCard diagnostic screens periodically. I have seen it where one or both card conditional access screens are not showing the perfect messages all the time.
For example, I just checked and Card1 is Missing_Program_Key and CA enable: unknown. Card2 is fine.
I am watching the Dallas-Minnesota game on HD without issue. I have checked the other tuner and everything is fine. If I check this tomorrow, Card1 will probably be fine and Card2 might say it's "having a problem". I won't have called anyone, nor would I have rebooted.
I have battled pixelation (not right now by the way and I have my own unsubstantiated suspicions of why this has happened) and posted when I have, but as of the last couple of weeks (knock on wood) have been clear.
The Diagnostic screen tells me what I already know - if the signal doesn't lock and it fluctuates, you will get pixelation. Why does this happen, beats me.