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Flaxaren: I bought this game just a couple of minutes ago and had the same problem (Windows 7). Just change the directrory when you first install the game.

Do not use the default one: PROGRAM FILES (X86).

Just put it somewhere else, i put mine in some folder under D:, but anywhere should work.

Happy hunting. :)
This worked. Just install somewhere else than default directory through the Options in the Installer.