I found I can clear the problem by deleting the 'temporary internet files'
Tools-->DeleteBrowsingHistory-->TemporaryInternetFiles
This reliably clears the the problem in IE7, but does not stop it happening again (when you right click on the link, select save target as, hit cancel, and left click the link).
The equivalent action in other browsers may work too.
Note . To clear the problem it is NOT neccessary to delete Cookies or History or FormData, or Passwords in IE7, nor is it necessary to logout of the site and log in again, nor its it necessary to restart IE7.
Last edited by Stewee (2008-02-29 16:19:57)