From my engineer computer geek son--
There is some nasty program going around being named Rasomware. Basically it installs it's self onto your computer and encrypts all your video, pictures, personal files etc. Then if you want them back, you must pay them $300 with in 72 hours. If you wait past that time, it goes up to $4k. They even set up an online pay site to make it easier for you to pay them and get your unlock code.
CryptoLocker crooks launch new 'customer service' website for victims - TODAY.com
Looks like there is really no defense against it, except a little computer savvy sense. Turns out the program is delivered in a zip file disguised as an update through an email. Like "Your outlook program needs to be updated, please download and open this zip file"
So, as always, don't open any files from people you don't absolutely trust. And never open any .exe file unless you've downloaded it straight from the source.
Oh, and sometimes the program even encrypts your backup. Neat.
Trust no one!