I believe this will fix it.
onClipEvent(enterframe)
{
if (this.hitTest(_root.enemy) && _root.userHealth <= 0)
{
gotoAndPlay(scene # of gameover frame);
}
}
I had a similar bug when I was creating PAC-MAN and that fixed mine. Good luck. Cheers! Also I suggest you have all your variable declaration on the first frame, the write the game on frame two. It will help with initializing and stop from resets.
Another thing, why do you have...
if (this.hitTest(_root.enemy) && _root.userHealth <= 0)
It is saying if this hits the enemy and your health is 0, game over. I suggest you have...
if (this.hitTest(_root.enemy) || _root.userHealth <= 0)
Note: || means OR.