And before Y2K, came Melissa.

A voracious virus that arrives in the form of an email document listing Web pornography sites threatened to cause havoc in corporate America Monday. Melissa, which seems particularly attracted to

Microsoft's

(MSFT) - Get Report

Word 97 and Outlook address book, can send up to 50 additional versions of the email to other users.

That could create a flood of unwanted emails as the program perpetuates itself. The news of the virus broke on Friday as it flooded networks of dozens of U.S. companies and forced the

Computer Emergency Response Team

, or CERT, at

Carnegie Mellon University

to put out its first advisory since 1994.

Wall Street, however, perhaps already getting in gear for the Year 2000 bug, appeared unfazed by the virus, although one

Bear Stearns

technical officer called it the fastest virus he had ever seen. "It could have been decimating to the email system," said the officer, who requested anonymity.

Overall, there were only isolated instances of the Melissa virus at Wall Street brokerage houses, as firms went into crisis mode on the weekend to deal swiftly with the problem before Monday. Fears were that as employees read their email, they would unintentionally spread the virus and thus infect their companies' intranets.

Bear Stearns

(BSC)

,

Donaldson Lufkin and Jenrette

(DLJ)

and

Charles Schwab

(SCH)

had minor outbreaks of the virus the previous Friday until "patches," or software fixes, were installed by technical departments.

"Everyone freaked out because

Melissa was unknown, but it really wasn't that big a deal and the anti-virus companies had developed patches to fix the virus within hours," says Bruce Schneier, president of

Counterpane Systems

, an Internet consulting firm.

The Melissa virus itself is part of a family of digital bugs that prey on macro functions in the newest version of Microsoft Word. Melissa quickly replicated globally because the email seems to be coming from a friend's or colleague's email address. "Important Message From

recognizable email address," is the subject line. Once the attachment is opened, the virus sends out email to the first 50 people on the user's address book and soon overloads a company's email server.

On Friday, problems first began popping up at

Merrill Lynch

, but by 4:15 p.m. Merrill's technical staff was on the case.

"We sent voicemails and intranet messages to our employees and brought down our network of servers shortly after," said Bobbie Collins, a firm spokeswoman. The company's network was brought back up Sunday afternoon, in time for the Australian stock market opening.

At Bear Stearns, a handful of people opened the attached file Friday, but after a weekend's worth of "hell," according to the technology support officer, the problem was contained. "But to have only a few detections of the virus out of 10,000 clients is really just a blip." DLJ,

Morgan Stanley

(MWD)

and

Goldman Sachs

officials weren't immediately available for comment.

A CERT official said that financial firms were not hit as hard by the virus, "perhaps because they were all so battle-ready for the Y2K problem."