It's a good start.
But it's not ping-pong, it's pong. You promise (in short desc) a fun and challenging game of ping pong, but you give us pong. The collision is bad, but again, it's a start.
Not sure if you've noticed, but the way you have your collisions set up, when the ball is going fast enough, it jumps straight through the paddles. Making it impossible to hit back.
The game could also do with some background audio.
Other than that, a decent start.
Thank you very much for your feedback. I am a beginner at using Flash to make games. I did notice the ball passes through the paddle when it reaches a high speed. That is because every time the ball hits a paddle, the amount of pixels the ball moves in one second multiplies by -1. The ball will keep speeding up until it moves so many pixels at once that it will teleport behind your paddle. That was our intention. If the ball did not pass through the paddle eventually, it would just keep going on and on and nobody would get the point. In this game, someone HAS to get the point eventually.