if you have multiple tv's, then grab a remote from another room, and bring it over and see if it does the same thing. if it's a bad remote, then doing that will reveal that problem.
Also try a to bring a cable box from the other room to this room with your TV. This will tell you if it's a cable box or remote control problem, and help you isolate what the problem actually is.
Before you do all that - try an stb auto fix, On your FiOS Remote, press Menu, then select Customer Support, and click on Fix FiOS TV Issues.