Magento Bug Fix

We have a bug in magento that we need fixed. Should be simple for someone who is a Magento Pro. We installed a slideshow extension and a datafeed extension, somewhere down the line it broke our magento e-commerce site. The problem: When someone creates and account and logs out and then logs back in to go shopping. As soon as you leave the user account page to go shopping magento says they are no longer logged in. If the shopper tries to put something in their cart magento says "1 item in your cart" but when you go to checkout by clicking on "my cart" it says no items are in the cart. However if we put "shop" on the end of the url address it seems to fix the problem. We really need to get this fixed. Should be simple. Example: [login to view URL] add "shop" [login to view URL] It clears the problem enough to allow the user to checkout. (all communication should be done through freelancer not through the contact form on [login to view URL]) Thanks!