Working with an Movie Clip as a button.

Question

I am creating a button with a 20 frame disolve into a page upon entry.  I want the button to play a 20 frame disolve back to it's original state when the user rolls out.  I want the movie clip to play from frame 21 to the end of the mc and then become inactive.  I can get the button to disolve out but the user will not be able to use it after that first roll over.  I was thinking of trying to add a time delay from when the first action of the rollout occurs to when the disolve is complete.  How do I include a 20 frame delay in the roll out sequence?
Here is my code so far:
//Index Button
mc_buttons.mc_index.onRollOver = function ()
    this.active = 1;
mc_buttons.mc_index.onRollOut = function ()
    this.gotoAndPlay (21);
//This is were I might include the time delay.  Any suggestions?
    this.active = 0;
mc_buttons.mc_index.onEnterFrame = function ()
    if (this.active == 1 && this._currentframe == 1)
            this.gotoAndPlay (2);
        }else if (this.active == 1){
        }else{
        this.gotoAndStop (1);
mc_buttons.mc_index.onPress = function ()
    getURL ('#');

Answer 1

The clip has a stop action at frame 1.  On rollover I want it to play at frame 2 until it hits the next stop action command at frame 20.  On roll out I want the clip to play at frame 21 and continue to the last frame (40) then loop back to frame one and stop.
So that the user can go back to the button after the first time I want the link to become inactive.  The frame rate is 32 fps so I only need a one second delay from the this.gotoAndPlay (21) command to the point where the link is de-activated, this.active = 0;, so that it can be activated again, this.active = 1;.
I found a line of code on another forum, setInterval(nextThing, 1000);, but it didn't work.
Any Thoughts?
Thanks