Preventing mask from becoming part of the MC?

programming flash
1

I have a movie clip with one word of text and mask that slides in to change the color of the text when moused-over. I also have an “actions” layer with the roll over code (posted below). As you can tell I am making a simple navigation button using a movie clip. However when I go the main root, publish the swf file, and mouse over the area to were the transparent mask is (to the right of the actual text), it activates the movie clip and starts to do the roll over.
How can I hide the mask so it is not an active part of the movie clip and only makes the text the only active part of the movie clip? I have tried adding a layer above the mask (on the main root level, not in the MC) and drawing a rectangle over the mask but this doesn’t help either.
Any ideas?
Let me know if I didn’t explain this well enough.

Here is the code that I have on the actions layer inside the movie clip:

stop();
this.onEnterFrame = function(){
if(rewind == true){
prevFrame();
}
}

this.onRollOver = function(){
rewind = false;
play();
}

this.onRollOut = function(){
rewind = true;
}

this.onRelease = function(){
getURL(“http://www.kirupa.com”,"_blank");
}