But how real is the threat?

A recent survey showed that for casual browsers who weren’t downloading music or file-sharing, the threat of getting anything nasty was low.

Those who ventured to gambling and porn sites were still at relatively low risk.

For those who download music or video from sites other than the recognised Apple or BBC or similar sites, the risk grew – downloading from torrent sites increased the risk significantly, though people who used torrent sites were generally pretty savvy, and dealt with any threats without any damage being done.

Those who used file-sharing programs such as Emule and Limewire were at the highest risk.

Limewire is a nightmare – it’s the computer equivalent of finding a used hypodermic syringe in a brothel and injecting yourself.

So,  keep your anti-virus and anti-spyware up-to-date, but don’t panic about the threat – it ain’t as bad as it’s made out, unless you use Limewire, in which case, you’re doomed.

The malware looks like an ordinary media download, but when the user tries to play it , they are prompted to install a codec to play the file.

If they comply, the computer is compromised and they are plagued by endless pop-ups.

Over 500,000 computers have been reported infected in the past week.