The inappropriately named "I LOVE YOU" virus is the fastest-spreading, most lethal electronic virus to date.
Early estimates on the costs to global organisations of the virus that crossed every continent in less than 24 hours are still unreliable, but it is expected to run into billions of dollars.
While the Pentagon and the House of Commons were among the highest-profile targets, the Japanese investment bank Nomura, and the telecoms firms Cable & Wireless and British Telecommunications were among the major companies to have their computers infected by the virus.
Those companies affected in the Republic were reluctant to disclose details, but it is understood many of the major banks, utilities, telecoms and software companies and Government Departments were hit.
The love bomb caused e-mail servers everywhere to grind to a halt as recipients unable to resist an e-mail carrying the subject field "I LOVE YOU" were prompted to activate the programme LOVE-LETTER-FORYOU.TXT.vbs.
The worm virus is hidden in an e-mail attachment and replicates if the message is opened, prompting Microsoft's Outlook programme to send infected messages to every user in the mail programme's address book.
Unlike its predecessor, the virus Melissa, which limited itself to just 50 people from the list, the Love Bug is less charitable.
The effect of so many messages being sent at once has the eventual effect of bringing e-mail servers within organisations to a standstill.
The Love Bug shares one characteristic with the Melissa virus in that it targets users of the Outlook e-mail programme. Last year Melissa tied up global e-mail systems and affected an estimated 1.2 million computers in North America alone.
In the US, the Federal Bureau of Investigation moved quickly to track the originator of the latest e-mail assault. It is thought to have its origins in the Philippines because the word "Manila" is included in the original e-mail. The original message comes from the e-mail address ispyder@mail.com
It also declares: "I hate to go to school."
The US-based originator of the Melissa virus faces a 10-year jail sentence for the mayhem he caused following last year's attack.
The perpetrator of this latest virus is likely to receive an even harsher penalty if convicted.
Anti-virus software companies were yesterday describing the Love Bug as the most devastating electronic virus to date, as details of the extent of its effects emerged.
It is understood the virus once activated also tries to download a file called WINbugsfix.exe which steals any keyboard-operable passwords stored on individuals' personal computers and attempts to send them to an address in the Philippines.
The Love Bug will also seek out sound and video files on a PC and overwrite them, giving them a Visual Basic file ending, rendering MPG and JPG files inoperable.
A Finnish computer security firm, F-Secure reported that one big media company had all its picture archives for the past two years deleted.
Mr Alec Florence, managing director of Priority Data Systems in Dublin said: "We are receiving four times as many calls about this virus as for the Melissa virus.
"Although it has little effect on business programmes, the e-mail overload is bringing companies to a standstill. The best advice we can give organisations is to disconnect or disable their e-mail servers, and anyone receiving an e-mail with "I LOVE YOU" in the subject field should delete it immediately."
Anti-virus software companies raced to sift through every line of code contained in the virus to identify possible effects.
As more was learned new versions of a partial fix were issued to companies, but, at best, were only capable of detecting the virus within systems yesterday evening.
Last night Mr Shane Colc lough, chief technology officer of factor-e at Irish Internet banking group enba, said: "Once we get the complete fix we still have to determine the full extent of the virus through a damage assessment and clean-up process. We've already lost one day's productivity, and I envisage our IT people will be dedicated to this problem for at least the next two days."
The effects of the virus are expected to be felt globally until Monday at least.