That "code" is a checksum. If you've reinstalled the game, it's really unlikely to be a game file that's incorrect. Check if you have any mods active. I don't know how the launcher works, but it's possible that the checksum on the launcher page is the value it's "supposed" to be, rather than what the game actually finds.
Failing that, you could have something like an out-of-place file. If you ever "modded" the game by manually installing files somewhere in the game directory, you'll need to remove those. Possibly the easiest way to check for such a thing would be to uninstall the game and look to see if any files are still there in the install directory.