Disable Auto Installs

The best way to solve a Windows update problem is to prevent it from happening in the first place. If you are concerned about contaminating your system with Windows Genuine Advantage or some other questionable update, instruct Windows not to install anything automatically: First, open Control Panel, and in XP's Category View click Security Center and then Automatic Updates. If you're using a version of Windows prior to XP--or if you're using XP's Classic View--either double-click the Automatic Updates icon or select it from the Control Panel menu.

Choose the option labeled Notify me but don't automatically download or install them (see Figure 1). That way, when you learn what updates Windows wants to install, you can read about them and check the latest opinions on the Internet before deciding whether they're worth the risk of installing. You can also ensure that your system won't reboot itself when you're not there, and, say, prevent your automated backup from running.