I would guess that your setup may be relying on the local cache initially, rather than checking the page on the server straight away. To test this, go to Tools, Internet Options, General. Then select Browsing History, Settings. This should be set to 'Check for newer versions of stored pages: Every time I visit the webpage'.
If that doesn't work, it may be a setting for your cookies, though if it is remembering you I'd expect the cookies are OK.
See how you go.