If you are experiencing strange behavior when switching users or switching roles, such as displaying of a different user's name at the top or unauthorized page access errors, it may be because your browser's caching setting is incorrect.

For Internet Explorer, this can be found in Internet Options -> General tab -> Browsing History -> Settings -> Temporary Internet Files tab. It should be set to "Automatically". If set to "Never", then it will never check for new versions of pages; it will always view the cached page and cause strange behavior.