The first thing I would check is your grip. Make sure it is strong enough to let your hands rotate the club face to square
The second thing I would check is the flex, sounds like your shaft may be to stiff for your swing speed
Understanding Golf Club Shaft Flex
Usually your ball flight will tell you where your error lies.
the rule of thumb is the direction the ball starts in is a result of the club head path, the direction it ends is a result of the face in relationship to the path