One large Irish organisation had to completely shut down its e-mail system this week after its network became infected with the Melissa computer virus. According to Dun Laoghaire data protection company Priority Data Group, about 20 other large companies and government organisations in the State had problems with Melissa as well.

"To a lot of people that might not sound like a lot, but they probably all had hundreds of machines infected," said sales manager Mr Joe Montgomery. He added that by Tuesday Britain reported some 60,000 PCs hit by the virus.

Despite the costly level of devastation that viruses can cause, Mr Montgomery noted that many - even large organisations - still do not use anti-virus software to protect systems. "We run across them every day of the week," he says. "They always say things like, it will be in next quarter's budget."

Priority Data says the top 10 viruses reported to its help desk recently were Ethan, CIH, ColdApe, Ska, Class, Ripper, Form, AntiExe, Laroux and NYB.

Meanwhile, Mr Scott Steinmetz, the man whose America Online e-mail account was apparently used to launch the Melissa virus, says he had nothing to do with its creation or distribution.

But he's getting plenty of e-mail since his name went out in media reports - everything from hate mail to admiring notes from hackers.