What the virus does is encrypt all files it has access to on your local computer which can include any network shares, USB hard drives, memory cards, backup system drives etc. Currently the only way to decrypt the files is to pay a ransom fee, but the decryption usually fails or never works. The only other way is to recover files from a recent backup.
This is a really nasty virus because its possible for your backups to be compromised depending on your backup strategy and network topology / server configuration.
Further information on the virus is available from the following link: http://www.microsoft.com/security/portal/threat/encyclopedia/Entry.aspx?Name=Trojan%3aWin32%2fCrilock.A
Getting your computer systems up to date on security and application patches is CRUCIAL to stop this virus entering your systems. You should regularly install any patches available from the MS Windows Update website and also update other software which includes – Java, Flash and any other applications installed on your system.
You should also ensure your backups are working and that backups are stored on multiple devices which aren’t all connected to a machine at the same time.
If you don’t know how to update your machines or perform a backup please let us know.