Simple Button Problem

Hi. I am trying to make a button out of a movie clip object. I attach a file for reference. Basically, I want it so the button has black text. When you hover your mouse over it, the text fades to pink, and when you roll your mouse off it, it fades back to black.

This works for me if I move the mouse slowly. However, If if move my mouse relatively quickly across the button, the Rollover action occurs, but not the Rollout. The button is now permanently pink, and when you move your mouse over it, it fades to black.

Any ideas what I need to do to stop this?