Borders problem

1

im making a semi-3D game and I have borders.

----Problem 1----
When the char hits the border he stops, but then I cant move after that, here is my actionscript


onClipEvent(load){
 speed=3
}
onClipEvent(enterFrame){
           if(!_root.bord.hitTest(_x,_y,true)){
 if(Key.isDown(Key.UP)){
  this._y -= speed;
 }else if(Key.isDown(Key.DOWN)){
  this._y += speed;
 }
 if(Key.isDown(Key.LEFT)){
  this._x -= speed;
 }else if(Key.isDown(Key.RIGHT)){
  this._x += speed;
 }
           }
}

----Problem 2----
Im trying to make it to where when you hit the tree you swap depths to become behind it, here is my as


onClipEvent(enterFrame){
	if(this.hitTest(_root.char)){
		_root.char.swapDepths(this)
	}
}

the problem is that I flicker

can someone help me?