There is a new virus out there called cryptolocker that encrypts all the files it finds on the local machine and on the network. If you get it, it is already to late to fix it, by the time you know it is on there. They say that if you pay them 300.00 then they will unlock your files, but there is a debate if anyones has actually been unlocked. Most anti-virus do not currently catch it, so it will walk right in.
Currently it is being sent out as a USPS.com notice that you have mail. But I am sure there are may variants of it.
Your only recourse is to remove the computer that was infected and reload it from scratch. Then restore all files that were encrypted from backup. It makes your backups really important!
Also backups that are update backups similar to carbonite, mozy, google cloud, skydrive, it will encrypt those files to because your backup software will see that the files were changed locally and will mirror them offsite.
External drives that use there included software do the same thing. Not Safe.
Full image backup similar to Macrium Reflect are not effected, so far.
They are saying that even the NSA could not de-crypt your files. This is currently only windows.
