Microsoft is currently addressing newly discovered holes in the security of their Vista and xp operating systems. Most importantly a security vulnerability in Windows Vista and XP that could expose a computer to an early-season bite while you are connected to the Internet.
How it works is a hacker can broadcast rogue TCP/IP packets to any range of IP addresses. The rogue packets have the ability to circumvent Windows’ security and hijack a computer turning that computer into part of a Bot net. Bot nets are designed for spamming as well as launching self replicating worms and even worse ICMP attacks which can shut down servers.
Currently there have been no attacks using this vulnerability. Microsoft scrambled to make available a patch to secure this hole and it is currently available using the link below. The patch may already be applied to your system if automatic updates are turned on.