Diagnosis
The remote's gyro sensor is getting interference. Usually from strong ambient light or reflective surfaces.
How to Fix It
Turn off or dim any bright lights behind you, especially LED or CFL bulbs. Cover any glossy surfaces (glass tables, picture frames) in front of the TV. Point the remote directly at the TV screen from no more than 10 feet away.
If That Didn't Work
Re-pair the remote. Press and hold the Back and Home buttons together for 5 seconds until the pairing message appears on screen. Follow the prompts.
Heads Up
The remote uses an infrared sensor for pointing, not Bluetooth. Never use cleaning chemicals on the sensor window at the top. It will cloud the plastic.