e is null or not an object - recursive function IE8 only

e is null or not an object - recursive function IE8 only

Hi JQuery Forum...
 
I have an issue when running the following recursive function using jQuery.  It was initially noticed on http://duplos.org/ it has a recursive function for iterating through each "Bubble" and randomizing the new bg-position.
 
Simplified version (of code):
 
$(div.bounceBubbles').each(
  function () {
   $(this).css({backgroundPosition: '5px 5px'});
   bounce(this);
  }
 );
 
 function bounce(currentA) {
  newx = Math.floor(10*Math.random());
  newy = Math.floor(10*Math.random());
  newspeed = bouncespeed + Math.floor(100*Math.random());
  $(currentA).animate({backgroundPosition: newx + 'px ' + newy + 'px'}, newspeed, 'linear', function() { bounce(currentA);});
 }











 
 
In Chrome and Firefox, there is no problems... figures.
My client would like it to run in IE8 the same, I have it doing just that, but after several hours the remaining js stops responding due to the null e.  The support stuff: using reference to http://code.jquery.com/jquery-latest.min.js reference, running Win7 Business and IE8.
 
Can some jQuery guru please investigate this problem.
 
Thanks