Historically, software cracks are a large source of malware. A user installs a crack to steal a copyrighted software and without their knowledge they have now become a zombie in a bot farm or start spamming email from their computer due to infections bundled with the cracks. Over the last couple of days we have seen a nasty brew of malware being masqueraded as software cracks that install a variety of malware such as rustock, TDSS, and IRCBots. Some of this malware will not be apparent to the user as they run in the background, but others will be quite visible. For example, when we examined these malware packs we have found all of them promoting the System Security and Antivirus XP Pro 2009 rogue applications. You will know you are infected because your desktop background will be set to black screen, as shown below, stating that "Many viruses were on your computer such as : Trojan horse, PassCapture, etc." You will also see numerous taskbar notifications stating that your computer is infected and when you click on the balloon, it brings you to the home page for Antivirus XP Pro 2009.
If you find that your computer has become infected as described above, I suggest that you use the following two guides as necessary to clean your computer. If you are still having a problem, as there is a good chance you will with this malware bundle, then you can post a question in our Malware Removal forum.