I was having the same problem and it turned out to be a problem with IE7. I had run the flush several times with no success so I tried it in FireFox and it worked the first time. Not sure if IE7 is unable to do the flush or if it was some caching issue, but you might want to try a different browser even if youÃ¢â‚¬â„¢re not using IE7.
Slurpdog - The web developers toolbar has a very handy and accessable 'clear cache' button which should be helpful! :)
DesignCity - Got it and use it regularly, but it wasn't working in this case for me. FYI: I prefer IE7 unlike everyone else at my work place that use FF and still have IE6 installed. I am also a designer and not a true programmer.