Have you enabled the captcha audio feature as shown in this online demo
? It is the only feature of RadCaptcha that could be causing the encountered behavior. Still, it is strange because usually the captcha control requires an installed Quicktime add-on and the Windows Media Player plug-in should not be necessary.
Please check if the popup displays when the page is opened on another machine. It is possible that the plug-ins in your IE installation are corrupted. There could be other elements on the page that are triggering the popup, remove the captcha to verify if this is the case. You can also open a support ticket
and send a simple, runnable page
that isolates your setup so that I can inspect the problem locally and provide a more to the point answer. A live URL to your page could also be useful for determining why the Media Player add-on is needed.
All the best,
the Telerik team
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