Quote from link below:
A new computer virus, Sobig, is spreading on the Internet, according to alerts posted by a number of antivirus software companies.
Sobig is a worm that uses e-mail and shared network folders to infect machines running Microsoft's Windows operating system, according to information posted on the Web site of Helsinki antivirus company F-Secure.
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The worm arrives in e-mail messages from a single sender, big@boss.com, and is stored in attached executable files with names such as Sample.pif, Untitled1.pif, and Movie_0074.mpeg.pif, according to F-Secure.
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From (Full article here)www.pcworld.com/news

Thanx for the warning,bedstor!