KUALA LUMPUR, Mon. - The vulnerability of computer systems was exposed again today when a virus dubbed Chernobyl was triggered, destroying database and hardware. Chernobyl, a sophisticated but malicious programme designed to covertly destroy computer data and hardware, rendered the PCs totally useless besides corrupting valuable database and causing irreparable damage.

The Malaysian Computer Emergency Response Team (MyCERT) confirmed that they received SOS calls from seven corporations and one home user but did not rule out that more were affected.

Going by the technical name of CIH 1.2, Chernobyl infects only PCs using Microsoft Windows 95 and Windows 98 operating systems.

The virus spreads through the Internet, especially by e -mail. Infection happens when a user unwittingly opens the e-mail containing the virus or downloads software from the World Wide Web.

The CIH 1.2 appears only once a year on April 26.

The saving grace is that critical operations like bank teller machines or mainframe computer networks, the lifeblood of many corporations, were spared from the attack, primarily because these machines do not use the Windows operating system.

"The only thing we can do," the MyCERT official said, "is point victims to the right direction to get a fix for their damaged computers."

This particular CIH 1.2 goes by the Chernobyl name because it was programmed to commemorate the 13th anniversary of the Russian nuclear accident in Chernobyl, one of the world's worst technological disasters.

Once downloaded, CIH 1.2 can lay dormant inside a hard disk for a long time without the owner realising it, unwittingly triggering the virus should the computer be started on the 26th of the month.

One senior information systems manager of a publishing company rued over lost data, especially telephone numbers and e-mail of valued sources, suppliers and other contacts.

"I was caught unawares when I shouldn't," he conceded. "When I booted my PC, this morning, it simply went kaput. Then I realised that today was virus day."

The manager said 30 PCs were infected but by late afternoon, most of the machines were revived but at the expense of lost data and precious man hours.

Some machines may have to be replaced while others need basic software to be re-installed.

However, another information systems manager who supervises machines using Windows 95 and Windows 98, was relieved that the PCs under his charge escaped unscathed.

"I don't use any special anti-virus software on my PC nor do the machines under my supervision," he said. "It's just that I strictly control and scan the software downloaded from the Internet. That's just being safe."

"Another safe method is not to open your computer on the 26th," he said.