Hi Linda,

Many thanks for your reply, I haven't got time to check the things you mentioned yet, but I discovered something just now when adding more Priced By Attributes products: if I disabled Dynamic Price Updater, the "background add to cart" problem does not occur. I've tried this on the latest Safari, Firefox and Chrome.

I was using version 3.0 of the plugin and I just found out that there is a newer version that came out last month but I haven't tried that yet.
http://www.zen-cart.com/downloads.php?do=file&id=1301

Will report back when I have more information.