When I add a product to cart, it shows up in the cart, but vanishes on a page refresh/when adding a new product. There are 0 rows in the WPSC_TABLE_CART_CONTENTS table, so doesn't look like the script ever inserts them there. Session ID remains the same.
I'm running WP 2.8.1 and WP eCommerce 3.7 and slightly (only CSS) modified Vanilla Cart theme (same problems happened with the default theme, too).
Any help would be very much appreciated. Thanks!