JQuery :: Auto Slider Speeds Up With Upgrade

After upgrading from 1.5.1 to 1.6.1 the auto-play feature of this slider speeds up. I'm using this code: [URL]. 4000 milliseconds is specified in the script if you view source, however, if you let the slider run for a few minutes(I haven't determined a consistent time frame for this) then the slider begins to change one after the next almost immediately without waiting 4 seconds.
.attr() is used once in the script, but after reading the core teams suggestions regarding .attr() after upgrading to 1.6.1 it doesn't seem like I'm supposed to change anything.

Same problem with this slider which is from [URL] simple-jquery-image-slide-show-with-semi-transparent-caption:
<script type="text/javascript">
$(document).ready(function() {
//Execute the slideShow
slideShow();
});

function slideShow() {
//Set the opacity of all images to 0
$('#gallery a').css({opacity: 0.0});
//Get the first image and display it (set it to full opacity)
$('#gallery a:first').css({opacity: 1.0});
//Set the caption background to semi-transparent
$('#gallery .caption').css({opacity: 0.7});
//Resize the width of the caption according to the image width
$('#gallery .caption').css({width: $('#gallery a').find('img').css('width')});
//Get the caption of the first image from REL attribute and display it
$('#gallery .content').html($('#gallery a:first').find('img').attr('rel'))
.animate({opacity: 0.7}, 400);
//Call the gallery function to run the slideshow, 6000 = change to next image after 6 seconds
setInterval('gallery()',6000);
} function gallery() {
//if no IMGs have the show class, grab the first image
var current = ($('#gallery a.show')? $('#gallery a.show') : $('#gallery a:first'));
//Get next image, if it reached the end of the slideshow, rotate it back to the first image
var next = ((current.next().length) ? ((current.next().hasClass('caption'))? $('#gallery a:first') :current.next()) : $('#gallery a:first'));
//Get next image caption
var caption = next.find('img').attr('rel');
//Set the fade in effect for the next image, show class has higher z-index
next.css({opacity: 0.0})
.addClass('show')
.animate({opacity: 1.0}, 1000);
//Hide the current image
current.animate({opacity: 0.0}, 1000)
.removeClass('show');
//Set the opacity to 0 and height to 1px
$('#gallery .caption').animate({opacity: 0.0}, {
queue:false, duration:0 }).animate({height: '1px'}, { queue:true, duration:300 });
//Animate the caption, opacity to 0.7 and heigth to 100px, a slide up effect
$('#gallery .caption').animate({opacity: 0.7},0 ).animate({height: '100px'},500 );
//Display the content
$('#gallery .content').html(caption);}
</script>