But there's no danger from an infected document , since opening it wouldn't run the infection, merely display the virus' programming. These hybrid documents do need to be scanned for viruses. The viruses that infect them are the notorious macro viruses such as Melissa , which wrecked havoc several months ago. Macros make Word and Excel powerful and convenient, but they also pose this security risk. It's not really protection, just a warning when a document contains a macro.
Webpages are another type of hybrid document.
In the early days of the Internet, webpages were pure documents, containing nothing but text and graphics. But in recent years, executable code has been attached to many webpages. Your browser's preferences will allow you to partially or completely block them, but this would severely handicap your web surfing in many cases. If the extensions aren't displayed on your computer, open any folder, go to the View menu, choose Options , select the View tab, and uncheck Hide MS-DOS file extensions for file types that are registered .