Javascript double refresh issue in IE

I'm finishing up an e-commerce website, and I can't quite figure out why the shopping cart feature is acting all screwy in Internet Explorer. It works fine in Firefox, but in IE, when you add a product to the cart it doesn't display the little pop-up notification, and when you click on the "my cart" at the top right the product quantities are incorrect about 70% of the time. For some reason IE keeps doubling the quantities; I think one of the scripts may be double refreshing the page I just can't figure out where.

If anyone has any suggestions they would be much appreciated.

The site I'm referring to is here:
www.tcatvs.com

Thanks y'all!

Also I'm using the jquery framework for much of the site.

Have you debugged???

Every page gets an error on line 112 "Object doesn't support this property or method".

And when you click on add to cart, there is an error on line 4370 "Invalid argument".

The MSIE debuggers aren't anywhere near as good a Firebug, but they are better than nothing. Install one and track down your errors.

Ahhh...Firebug *ALSO* complains about line 112!!!

Error: jQuery("form.product_form").livequery is not a function
Source File: http://tcatvs.com/wp-content/plugins/wp-e-commerce/js/wp-e-commerce.js?ver=3.746
Line: 112

But it has no problem with line 4370.

I saw this cross-posted on stackoverflow.com.

I find it odd that your Ajax response is a ton of jQuery code with embedded markup. Why not make it simple and return a JSON object or XML to parse?