"Microsoft told Windows XP users today not to press the F1 key when prompted by a Web site, as part of its reaction to an unpatched vulnerability that hackers could exploit to hijack PCs running Internet Explorer (IE). In a security advisory issued late Monday, Microsoft confirmed the unpatched bug in VBScript that Polish researcher Maurycy Prodeus had revealed Friday, offered more information on the flaw and provided some advice on how to protect PCs until a patch shipped.
"The vulnerability exists in the way that VBScript interacts with Windows Help files when using Internet Explorer," read the advisory. "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."" – Content courtesy of Microsoft: Don’t press F1 key in Windows XP