1 - Remember where (in which directory) you've installed the game.
2 - Uninstall it again through the uninstaller provided with the game.
3 - Check the directory where it was installed, DELETE it and any files that are contained in it if it's still around (the uninstaller might be keeping changed / modified / newly created .ini and profile files on the HDD even after you make the automatic uninstall, that's why you need to make sure that EVERYTHING relating to the game is gone)
4 - Reinstall the game, see what happens.

If the above didn't help and you're computer savy enough, there's also Step 3 1/2 - follow the first three steps again, then check if ALL registry settings relating to the game have been removed by the uninstaller, if not remove them manually. If you don't know how to do it, just skip it, as it's too long to explain

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