(CBS News) An Internet worm that's been circulating for a couple of weeks is set to destroy files on infected personal computers this Friday, Feb 3. Security company Symantec has dubbed it "W32.Blackmal.E@mm," but other security companies have given it different names including "Nyxem," "blackworm," "Grew.A," "My Wife" and "Kama Sutra." Whatever it's called, it has already infected 300,000 systems, according to the Sans Institute.

The worm is spread by e-mail. It tries to harvest e-mail addresses from infected machines so it may appear to come from someone you know. Unlike many past worms, it is not limited to Microsoft Outlook or Outlook Express all Windows users are vulnerable but it affects only Windows not Macintosh, Linux or other operating systems.

It watches your PC's clock and is set to delete files from infected machines on Feb. 3.