How to increase speed of a mc and also stop it?

programming flash
1

hi i wish to increase/decrease the speed that the mc plays (frames are inside the mc) but if the mc reaches a certain frame it should stop.

I have the code for stopping-

this.onEnterFrame = function() {
Cholesterol.play();
if (Cholesterol._currentframe == 10) {
Cholesterol.stop();
delete this.onEnterFrame;

here is the code for the speed-

function playMovie(){
holder_mc.gotoAndStop(holder_mc._currentframe+1);
}
playID=setInterval(playMovie,100)//10 frames per second

but the two peices of code seems to cancel eachother out.
Thank you for the help