First we need to know a lot more about your computer and the exact version and variant of MEP you are running. Please read this post and give us ALL the information requested there. Thank you.
Then you need to tell us rather more about this audio track. Where does it come from? What format is it, e.g. .mo3 or .wav? How long do you expect it to be?
With all the above we may be able to offer you some advice.