source: http://www.securityfocus.com/bid/20875/info

Microsoft Internet Explorer is prone to a denial-of-service vulnerability. This issue occurs when Internet Explorer attempts to parse certain malformed HTML content.

Successfully exploiting this issue will cause the affected application to crash, denying service to legitimate users.

Internet Explorer 7 is vulnerable to this issue; other versions may also be affected.

Content-Type: text/html; 
charset="windows-1251" 
Content-Transfer-Encoding: quoted-printable 
Content-Location: about:blank 

<iframe name=ifr src="">