Many subscribers of MSN.co.uk were told that the site was infected by a virus when they logged on this morning. But it was a false alarm.

Surfers using Norton Anti-Virus are told that a Trojan horse has been detected in a Vbs (Visual Basic Script) file on the site (www.msn.co.uk/webinclude/mc.vbs), which will appear in the cache of a user's browsers after visiting the site.

But the file is harmless and the alert is a false positive, according to Eric Chien, chief researcher at Symantec's Anti-Virus Research Centre.

Over-sensitivity in the automatic detection of viruses (or heuristics) included within Norton Anti-Virus is to blame. "You have to strike a balance with heuristics and sometimes you can get it wrong," he said.

The next update to Norton Anti-Virus signature definition files, which Symantec releases today, updates users' protection so they can visit MSN.co.uk without receiving a warning. ®

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