Not a bad concept, although a simple game.
It lagged like all hell, and the music got ridiculously annoying in the long run, but it seems pretty promising. You really need to sort out the lagging issue, because that's what mostly killed it. I'm no actionscripter, so I can't help you with the technical stuff, but I would recommend that you ditch the textures in favor of solid vector blocks or something.
Mess around with the code a bit, come up with a few more clever levels. If you can get it running smoothly, it'll be neat.