hitTest glitch with ball and wall

I’m making a game where the ball bounces off several walls to get to its destination: the portal. When the ball reaches a high speed it glitches through most of the walls.

Here is my scene for the 3rd level of my game where the most glitches occur:( (attached file)
In the picture there lists all the variables i put in the objects. You will also notice that I put a “Stuck” button since there were many glitches.

Here is my code within the ball(hero):
onClipEvent (load) {
power = 1;
yspeed = 0;
xspeed = 0;
friction = 1;
gravity = 0.5;
thrust = 1.6;
}
onClipEvent (enterFrame) {
if (Key.isDown(Key.LEFT)) {
xspeed -= power;
}
if (Key.isDown(Key.RIGHT)) {
xspeed += power;
}
if (Key.isDown(Key.DOWN)) {
yspeed += power*thrust;
}
xspeed = friction;
yspeed += gravity;
_y += yspeed;
_x += xspeed;
if (_root.wall2.hitTest(_x-(this._width/2), _y, true) or _root.wall2.hitTest(_x+(this._width/2), _y, true)) {
xspeed = -1;
}
if (_root.wall1.hitTest(_x, _y-(this._height/2), true) or _root.wall1.hitTest(_x, _y+(this._height/2), true)) {
yspeed = -1;
}
if (_root.bounce.hitTest(_root.hero)){
_root.hero.yspeed
=-1;
}
if (_root.bounce1.hitTest(_root.hero)){
_root.hero.yspeed
=-1;
}
if (_root.bounce2.hitTest(_root.hero)){
_root.hero.yspeed
=-1;
}

if (_root.portal.hitTest(_x, _y, true)) {
_root.gotoAndStop(4);
}
}

Can anyone help me fix the glitching problem?