Referred to as one of the deadliest computer viruses ever, Melissa, a Microsoft Word macro virus, is replicating itself across the Internet through Microsoft Outlook-based email. How serious is Melissa? Well, this is the first time the U.S. government has released a warning about a computer virus, so it's actually pretty serious, unlike previous virus threats such as Michelangelo. Security experts are saying that Melissa contaminated all kinds of government, military, and commercial email systems over the weekend, including Microsoft's internal email.

The Melissa virus can affect anyone using Word 97 or 2000 with Outlook 97 or 2000. Melissa is delivered as a Word document attached to an email message. The subject line contains the text "Important Message From "UserName" and/or contains the text "Here is that document you asked for ... don't show anyone else ;-)" in the message body. Anyone who is affected by this virus will discover that Outlook has forwarded the infected email to the first 50 users in their address book.

So how do you protect yourself from this? Well, by default, Word 97 and 2000 are setup to protect you from macro viruses, so be sure to turn this back on if you've disabled the feature. In Office 97, you can enable this feature by opening the Word Options dialog (Tools-->Options) and finding the "Macro Virus Protection" option on the General tab. In Office 2000, you must choose Tools-->Macro-->Security and then select High or Medium security.

If this virus has already attacked you, make sure your macro security settings are turned back on as the virus can disable this feature.

For more information about Office viruses in general, please visit the Microsoft Anti-Virus Center. The company also has some Melissa-specific information on the Office Update Web site