source: http://www.securityfocus.com/bid/10997/info

Opera Web Browser is reported prone to a JavaScript denial-of-service vulnerability.

This vulnerability presents itself when Opera attempts to execute a specific JavaScript command. When executing this command, Opera will reportedly crash.

This issue affects Opera 7.23 for Microsoft Windows; other versions are also likely affected. 

<scr1pt>
document.getElementsByTagName("script")[0].text = "";
</scr1pt>