Help with Delaying a function!! Please

[cpmartin]

Thank you in advance for looking at my question.

This is my code:

function loadCurrentPage(newPageNode) { 
    btn_next._alpha = 50; 
    btn_next.enabled = false; 
    millisecondsToDelay = 25*1000; // 21 second
    myFutureFunction = function() 
{ 
  clearInterval(ih); 
  btn_next._alpha = 100; 
    btn_next.enabled = true; 
  // do future stuff here... 
} 
ih = setInterval(myFutureFunction, millisecondsToDelay); 
//Enables Next button after 20 seconds (Table of Contents). 

s

I am trying to delay when my next button will become enabled. The millisecondToDelay works but after a while it starts to gain and lose time. It is unreliable. Is there a frameToDelay that I could use?