A new virus was launched today that exploits the security hole acknowledged by Microsoft on July 16. (See my writeup on August 4.) You’ll likely see newspaper articles on Tuesday with more details.
Systems protected by a home router or firewall probably aren’t affected. I was working on a system Monday afternoon that crashed in an unusual way – and sure enough, we were on a dialup connection without a firewall.
So please, don’t delay: go to http://windowsupdate.microsoft.com and install Critical Updates, and update your antivirus software.