scrollLeft - scrolling a div

[spenoir]

I have this simple script for scrolling a div:

function ScrollLeft()
{
  Timer = setInterval("document.getElementById('scroller').scrollLeft -= 2", 15);
}
function ScrollRight()
{
  Timer = setInterval("document.getElementById('scroller').scrollLeft += 2", 15);
}

It works cross browser, but it breaks pretty easily if you fiddle with it a bit
Anyone got a better method of scrolling a div or a way of fixing this one. I was drawn to this method for its simplicity.