Does it result in a blank screen with just a hashmark("#")? I am sorry I don;t have a solution, but if it is the same issue - the items are in the cart it is just inconvenient that the end user has to log out and back in again- at least in my case. I have trouble reproducing it and my developer team team cant pin it down either. I hate to tell end users to log out and back in again and use Firefox in the future if they dont want that experience again. Let me know what you find.
You need to disable the XSS filter in the custom level setting of the trusted sites in IE.