I think what he's referring to is a message that comes up occasionally when you go back a page and IE needs to resend some data to the site. It gives a warning message saying that the page needed IE to resubmit some "form data" and for security reasons IE has blocked that request. (Hence the Warning: Page Has Expired message) From the wording of the message, you get the impression that there is a security setting you can change that will correct this but I've never found it. You have hit refresh to force the page to reload. I would commonly get it on Fusetalk forums, including here, if I was reading threads that I found via a search - hitting back to go back to my search results would result in the error. Newegg would give me the problem if I had something in my shopping cart and wanted to just go back to the product menu instead of clicking the 'continue shopping' button and have to renavigate that catalog, etc.
I never found a fix but after my last XP reinstall, I don't have the problem anymore.