Startling new information comes to light in this article from Today Money, dated today. A new, nasty piece of malicious software, CryptoLocker, is infecting computers around the world — encrypting important files, even your photos —and demanding a ransom to unlock them. It says a typical extortion payment is $300. One business received an email attachment that looked like a shipping invoice from U.S. Postal Service.
Anti-virus software can not undo the damage, according to the NBC news writer. Backing up is the only way to reduce the risk of losing your files forever, however he also warns your backup device should be disconnected from your computer until the next time you need to access it. The article gives more details.