Sound class bug in AS2

So heres the thing, I’m building a pacman game at work, and the whole game works just fine, and like the original game, when pacman eats a little “dot” thingy the game plays a sound. Every thing is cool up to here, except that when played on Vista, every time pacman eats a little dot thingy the game bugs, slows down alot, and then runs smoothly again… it does this anytime you eat a dot thingy, and only on vista.

anyone got any idea as to how to fix the bug or any info relating to it ?