[JeffM]

I'd bet that your are tensing up because of apprehension and you are looking right in front of the bike instead of down the road. Where are you looking and what is your body position while taking these corners? Are you leaning the bike or trying to keep it as upright as possible?

After you let off the brake(s) what do you do with the throttle? What gear are you in?

Remember, maintaining a little throttle while cornering stabilizes the bike. Be very smooth and deliberate when transitioning between being on the brakes and rolling on the throttle. Indecision and choppiness with the throttle during a turn will upset the bike.

Take your time and do not rush your learning and be safe.

Jeff