something in the CSS IS breaking the javascript.
delete the form tag that is around the quick cart buttons, then add links instead:
<a href="../checkout/shoppingbasket.php"><input name="VVcart_View_100" type="image" class="eC_ImageButton" id="VVcart_View_100" src="../images/VV_button_ViewBasket_100x25.png" alt="View Cart" /></a>