A COMPUTER bug which targets Microsoft software brought down the IT network of a local authority yesterday.

The "worm", dubbed the Sasser bug, uses e-mail to access systems.

Once opened on the network, it can spread quickly to other unprotected terminals without the user doing anything.

It is thought the bug got into North Yorkshire County Council's network via e-mail sent to the Press office, scrambling communications and spreading to half a dozen other computers before it was detected.

Staff found they were unable to open e-mails, and desk top icons either vanished or became corrupted.

The authority immediately shut down all its computer systems to isolate the worm before launching a procedure to repair the damage.

"The problem is that the council has grown in such a way that different departments use different systems," said spokesman Tony Webster.

"We are in the process of rolling out a standardised computer desk top across the authority which should limit the chances of this sort of thing happening again. Hopefully, the process will be complete in a couple of months."

The Sasser bug, which targets Microsoft's Windows 2000 and Microsoft Windows XP software in particular, can also slow computers' processing speed and crash them.

On Tuesday, it hit coastguard systems across the UK.