Button Help again!

Hi I have just started creating a set of buttons, but the problem is when I rollover on the button just randomly the movie clip keeps on looping or repeating, but when I place the cursor over the base of the button the button stays on its rollover state like I want it too. Could I fix this by making an invisible button and placing it over the top of my button to stop this from looping. Or is there any alternative methods I could do to stop this?

Cheers

Craig

PS. I have inserted the Fla. file if this helps.