change the movement
id suggest you try this
onClipEvent (load) {
x = y=0;
}
onClipEvent (enterFrame) {
_x += x += (Key.isDown(Key.RIGHT) && x<10)-(Key.isDown(Key.LEFT) && x>-10);
_y += y += (Key.isDown(Key.DOWN) && y<10)-(Key.isDown(Key.UP) && y>-10);
x *= .9;
y *= .9;
}