One of the first rules of security alerts is never follow any instructions received in an email, to delete any files or folders on your computer without verifying the warning. To verify a warning, use your own anti-virus software provider or one of the trusted companies listed in the far right-hand column, headed "Anti-virus links". Even a warning email from a trusted colleague should be ignored until verified.

If you're paying a yearly subscription to keep your anti-virus software up-to-date, then do yourself a favour... uninstall it and install AVG Anti-virus 7.5 Free Edition. You don't hear much about it in computer mags, because they don't advertise, but it's more than up to the job and it's free.

More information can be found in the Online Security section.