We have upgraded a second NOP 4.0 site on our server running windows web server 2008 R2 with IIS 7.5. The original 4.0 site was running without problems. After upgrading the second site from 3.9 to 4.0 neither of the two sites shopping carts work.

You can add a product to the cart but when you attempt to access the cart the products are not in the cart.

I'm not certain if this is an IIS issue or a NOP 4.0 issue. Any help would be appreciated as we now have two production sites down.