open your steam account,right click on cliffs of dover and click on properties.then go to the local files tab and verify integrity of game cache-this brings you back to the official version.
after doing that start the game once(dont know if you actually need to) and exit again.after that go to your 1c folder and clear the cache folder(delete all files in it except the subfolder, but delete the files in it as well)
after that you can install the previous beta and you are ready to go.
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