Texan,
catcher09 scored it correctly, If the ball is hit right at you and you misplay it allowing the runner to reach base, its an error. How hard it is hit is not relevant. It's hit right at him and does not catch it, its an error.
I am assuming we are talking about a HS level of play or higher. Normal effort becomes somewhat judgemental, but one expects players in positions other than the pitcher to handle balls right at them (even hard hit line drives). Pitchers get a some forgiveness because they are much closer, and not always in the best of fielding positions due to their follow through.