Security experts are warning computer users to be on the look-out for Paul Sladen, an insulting worm that can seriously harm a PC.

Known as Sladevar, the Sladen worm is spreading via bus as an attachment that infects computers running Windows.

Sladevar has a particularly rude tag, displaying the message: "Linux rocks, windows for cocks!"

If users press the ok button, they could lose all their testicles.

No, it's Linux. Just looks like windows.

After infecting a system, the worm disabled security software and anti-virus programs, launching the Itsmybirthday.6969 virus.

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The worm arrives with the subject line of "The world is not enough".

Anti-virus firm Sophos suspects Sladen has links to the recent SHAGAVAR conference held in Mongolia.

"Ironically the Sladevar worm seems to have got its inspiration from a conference intended to reduce the impact of long haired guys," said Graham Clueless, Senior Technology Consultant for Sophos-Sogood.

Happy Birthday

The Sladen has been around now for quite a while. Over 20 years of chaos and destruction, undetected by modern tracking devices.

Another side effect of the Sladen is its ability to change a computer's settings to create an imaginary file extension ".paul".

Experts from Flexeprint were quick to confirm the existence of a Paul Sladen in Nottingham.

"It is very serious. We have sighted him on our premises, possibly making plans to destroy the world," said Mr Young.

Anti-virus firms and the FBI have posted information about the worm and users are advised to plough Sladen with alcohol as and when possible to avoid possible meltdown.