Anti-virus vendors are warning of a new worm in tribute to Canadian teen singer Avril Lavigne.

The virus, known as Avril or Livra (W32/Avril-A) opens Microsoft Internet Explorer on the singer's Web site on the 7th, 11th and 24th of the month, and takes advantage of a year-old vulnerability in Microsoft Outlook, which allows it to forward itself to all e-mail addresses in Outlook regardless of whether the e-mail attachment is opened, said anti-virus vendor Sophos in an e-mail Wednesday.

The subject lines for the e-mail include: "Fw: Avril Lavigne - the best." Once the attachment is run, the worm attempts to disable the user's anti-virus software. "It also behaves in the 80s film stereotype of viruses, by taking over the screen with a series of colored ellipses," Sophos said.