random movement

[tibbi]

hey, Im new at flash, but Im learn as2 :P
so my problem is that I want to spawn a ball to the middle of the screen, and want it to move with constant speed in random direction everytime its spawned. it sounds really easy, but I cant make it work...
current code Im using for the ball movement is

function setBehavior(Ball:MovieClip):Void
{
	var randomAction = random(2);
	switch (randomAction) { 
	case 0 : 
Ball.xSpeed = Math.random(Ball.mySpeed)*Ball.mySpeed;
		break; 
	case 1 : 
		Ball.xSpeed = -(Math.random(Ball.mySpeed))*Ball.mySpeed;
		break; 
	default : 
		break; 
	} 
	
	var randomAction = random(2);
	
	switch (randomAction) { 
	case 0 : 
		Ball.ySpeed = Math.random(Ball.mySpeed)*Ball.mySpeed;
		break; 
	case 1 : 
		Ball.ySpeed = -(Math.random(Ball.mySpeed))*Ball.mySpeed;	
		break; 
	default : 

		break; 
	}
}