Bethesda has released a new update for the PC version of The Elder Scrolls V: Skyrim which stops the use of third-party patches that change the executable file.

If you update your copy of Skyrim you will be unable to use third party patches that change the executable file in order to improve graphics and performance etc, such as one patch that allows the game to use more than 2GB of RAM in order to run more performance demanding mods. The update also forces all versions of the game to use Steam in order to prevent piracy so people can no longer circumnavigate the service.