Symbol Gets Stuck on Edge Occasionally - actionscript-3

Question

I have some code whereby I want a symbol (just a square atm) to bounce around inside the stage. Occasionally however, it gets stuck on the edges. Any advice on how to fix this?
Everything else works fine, including the inertial motion.
package {
import flash.display.MovieClip;
import flash.events.*
import flash.ui.Keyboard
public class Unit extends MovieClip {
var velocityX:Number = 1;
var velocityY:Number = 1;
var accellerationX:Number = 1;
var accellerationY:Number = 1;
var bounciness:Number = 1;
var maxSpeed:Number = 10;
public function Unit(){
Key.initialize(stage);
addEventListener("enterFrame", move);
}
private function move(e:Event){
accellerate()
if ((this.x<10)||(this.x>780)){
velocityX *= -1;
if (velocityX>0){
velocityX -= bounciness;
}
if (velocityX<0){
velocityX += bounciness;
}
this.x += velocityX;
}
else{
this.x += velocityX;
}
if ((this.y<10)||(this.y>520)){
velocityY *= -1;
if (velocityY>0){
velocityY -= bounciness;
}
if (velocityY<0){
velocityY += bounciness;
}
this.y += velocityY;
}
else {
this.y += velocityY;
}
}
private function accellerate(){
if (Math.abs(velocityY) < maxSpeed){
if (Key.isDown(Keyboard.UP)){
velocityY -= accellerationY;
trace("Accellerating UP");
}
if (Key.isDown(Keyboard.DOWN)){
velocityY += accellerationY;
trace("Accellerating DOWN");
}
}
if (Math.abs(velocityX) < maxSpeed){
if (Key.isDown(Keyboard.RIGHT)){
velocityX += accellerationX;
trace("Accellerating RIGHT");
}
if (Key.isDown(Keyboard.LEFT)){
velocityX -= accellerationX;
trace("Accellerating LEFT");
}
}
if (Key.isDown(Keyboard.SPACE)){
velocityX = 0;
velocityY = 0;
}
}
}
}

Answer 1

Your problem is like the following:
if ((this.x<10)||(this.x>780)){
velocityX *= -1;
You toggle the volocityX, but what is likely happening is on the next frame, it still meets the if condition (hasn't moved far enough the other direction) so it's just going back and forth every frame from -1 to 1.
Do something like this instead:
if(this.x < 10 && velocity == -1) velocity = 1; //If it's near the left edge, and still moving to the left, change direction
if(this.x > 780 && velocity == 1) velocity = -1;
This way, you are only flipping the direction when it's going the wrong way.
Repeat for the velocityY stuff