CryptoLocker is virus that encrypts your data files (word, powerpoint, pictures, music, videos, etc.). Your data is then held for ransom and try to extort money from you.
CryptoLocker tends to get in through phishing emails with attachments which fool you into opening them.
Although the virus is quite easy to clean, the encryption cannot be by-passed, and infected files can only be restored from backups. If you have no up-to-date backups you may be at risk.
This is likely to be the shape of things to come – Cryptolocker is the worst virus I have dealt with.