Shipping & Tax Not displaying in shopping cart

Hi

I installed marketpress and HAD it all set up and working correctly.It has now developed a bug where the shipping and tax rows in the checkout table are not displaying. Yesterday this problem only occured in Internet Explorer and Safari (but was ok in firefox) but today problem has extended to all browsers ??

I'm running WP 3.1 with no other plugins except gravity forms which I have deactivated to check for a conflict but problem persists.

The site can be found at http://herb-garden.foodlvr.co.uk/

I'm more than happy to prvide wp login credentials if that will help for a speedy solution.

Thankks in advance for your help

Luke