Our site has just implemented a captcha using flash, and it also creates a wav file so users can play back the text if they can't read it. This works fine in IE and FireFox. In Opera, when I play the wav file the first time, it plays correctly. If I reload the page, I get a new captcha flash image, with different text, but if I play the wav file, it plays the previous one. If I manually clear the browsers history, reload the page again, it plays the correct wav file. It seems Opera is caching the wav file locally. When I click the wav file, it doesn't appear to call the server to get the wav file, it seems to play it's local copy. How can I get this working in Opera? I'm also using the following meta tags:

<meta content="no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0" http-equiv="Cache-Control"/>
<meta content="public" http-equiv="Pragma"/>