A virus is currently spreading via instant messaging systems. Just a moment ago, I received a message from a contact in my Windows Live Messenger that reads:

wtf?! its you on this photo (a malicious URL pointing to a Windows executable follows)

Please do NOT click on the URL if you received such a message or any other suspicious message. Clicking on it will cause the malicious program to be downloaded and installed on your computer. Once installed, the program will send the above message to all your contacts in your instant messaging software. And this explains how the virus continues to spread.