I'm a self confessed freezer over the ball as well. My symptoms are slightly different. When it comes time to pull the trigger, my hands, wrists and arms get very tense. A real killer. Oddly, no problems on the putting green or for pitching/chipping. I'm open to any suggestions others might have for fixing this problem.
Interestingly, Michael Breed on the Golf Fix addressed this problem the other night on his show. He suggested doing the following drill for 30 days:
1. On the range place 3 balls in row approximately 2 feet apart
2. Start swinging the club back and forth
3. Move towards the balls with the intent of hitting them on the fly
4. Prior to hitting each ball, look up and pick a target and then hit the ball
5. Repeat for 5 - 10 reps
Ultimately, it doesn't really matter where the ball goes. The purpose of the drill is to train your brain/body to react to hitting a ball. See ball, hit ball.
In order to take it to the course, he suggested incorporating certain elements into your pre-shot routine:
1. Take a practice swing beside the ball
2. Address the ball
3. Take one look and swing
At this point I've tried the drill on the range a couple of times in June and I've incorporated certain aspects of the pre-shot routine on the course. Modest results so far.