Has anyone encountered any strange behaviour in Flash? I've been working on a game for over a month and running in to problems that should not happen.

Example: Movieclip is in Frame 89 has a sound attached to it. Now on frame 55, before the movieclip in question, there is actionscript:

if (enemyKillsRequired == 12) {
} else {

If the player dies it goes to the game over scene. Midway through the gameover sceen the sound of the movieclip on Frame 89 plays despite the movie not reaching that frame! Also, when an enemy dies, there is a sound of them grunting. This also repeats even after the enemy has been killed and removed from the stage! Has anyone any idea of what may be going on? Developed on CS5.