Microsoft released a new security advisory regarding Internet Explorer on a Windows 2000 or XP system. To exploit the vulnerability,a malicious site reaches through the web browser by using VBScript and accesses “inherently unsafe” Windows Help files.
To complete the attack, a user must push F1.
The article at PC World suggests users to log off Windows or close Internet Explorer via Windows Task manager when a site prompts a user to hit F1.
Source: PC World