I can't say it has ever happened to me... so, what version of IE or Firefox (or Google Chrome, Safari, etc...) are we all using... this may help solve the problem.
To find the version: Click on "Help" and then "About" in your browser. (In IE 7 onwards, if you do not have the "Help" menu, click on "Tools", then "Toolbars" and then "Menu Bar" - this will show the help menu)
I'm using Firefox version 3.0.3
But I will test this in IE 8 beta.