Microsoft has released Security Advisory 981169 that details a zero-day vulnerability that could allow malicious code to be installed on your PC:
The vulnerability exists in the way that VBScript interacts with Windows Help files when using Internet Explorer. If a malicious Web site displayed a specially crafted dialog box and a user pressed the F1 key, arbitrary code could be executed in the security context of the currently logged-on user.
Sit tight and wait for Redmond to issue a fix. Sound familiar?