Antivirus researchers are warning their customers that the CIH virus has the capability to wipe out the user's data or disable a computer outright. The virus has spread via electronic mail and, upon hitting its trigger date on April 26, will drop a "payload," or a kind of electronic time bomb that could wipe out a part of a user's system that begins the computer's start-up sequence. Variants of the virus may also strike on June 26.

"It will leave your PC dead," said Vincent Gullotto, manager of an emergency antivirus team far Network Associates Inc.'s laboratories in Oregon. "It's a fast infector and it spreads itself until its payload date."

Antivirus companies are worried about the damage that CIH and its variants can do because it is so pervasive. The virus is believed to have originated in Taiwan, and Sal Viveros, a marketing manager at NetworkAssociates, says he is concerned Asian companies will be particularly vulnerable to the attacks. ``This could be disastrous,'' he said. ``It's the most prevalent virus in the wild now," or released in the computing world. The virus infects Windows 95, Windows 98 and Windows NT computers and disables a vital part of the computer known as the flash BIOS, which feeds the start-up instructions to the machine upon being the turned on. If the computer has chips that are vulnerable to the virus, then the computer won't start, or `boot."

In addition, the virus can corrupt data stored on the PC's hard disk drive. The virus isn't easy to spot because it copies its instructions into unused parts of programs that are already loaded on the user's computer. The best protection against the virus, experts say, is to run an updated antivirus program. They also advise against opening any unexpected e-mail attachments.

But many computers are already protected against the virus because it has been spreading since June,giving antivirus companies time to build CIH defences into their software. The virus spreads if some one uses an infected floppy disk or opens an infected e-mail attachment.

Earlier this month, IBM had to warn its customers who bought Aptiva PCs that their machines were infected. Network Associates said it has been getting reports of the virus from customers on a daily basis. Since the virus can be fatal to a computer, the researchers are most concerned about small businesses and ordinary users who don't regularly take precautions.

The Asian Wall Street Journal