A virus that spreads a list of pornography sites via e-mail hit computers over the weekend and threatened havoc yesterday as workers returned to offices and began opening messages sent over the Internet.
The virus, called "Melissa," comes in the form of a document that lists pornography sites on the WorldWide Web.
Computer experts said the virus was aimed at widely used Microsoft Windows-based e-mail address book software, Outlook and Outlook Express, and it can send up to 50 additional versions of the e-mail to other users, threatening a widespread infection of computer systems.
That could create a flood of unwanted e-mails around the Internet as the program perpetuates itself using pre-programmed "macros," software embedded in the Windows operating system that sets off complex computer functions with one command.
There have been reports from America of companies' mail servers being overloaded by messages created by the virus. Affected companies could no longer receive e-mail.
Anti-virus firm MacAfee reported that Melissa had hit 20 large US companies, including Microsoft and Intel, representing more than 60,000 computers.
However, experts were more concerned that when people returned to work on Monday and opened e-mail the virus would cause a massive increase in messages, further overloading servers.
"The proliferation of this virus is something we have never seen before," a spokesman for MacAfee said.
Computer experts warned users to be wary of documents sent from any senders asking them to open up a file for Microsoft Word.
That file, in turn, asks for a prompt asking users whether they want to initiate a "macro," and requires users to approve its use.
Those checkoffs make it relatively easy to avoid the problem.
