In September, a new type of trojan ransomware, CryptoLocker, started making the rounds by way of email attachments and links on infected webpages. It won’t destroy anything on your computers, just encrypt the data so you the user can’t access it.
Once the files are encrypted, a screen pops up directing the user to pay a ransom of $100 to $300 (or two Bitcoins) within three days to regain access to the files. Beyond the 72-hour deadline, the ransom rises to 10 Bitcoins (About $3000).
CryptoLocker itself is not difficult to remove, the damage comes from the encryption.