Webster

the thing to remember is even though you uninstalled the game, any "changed/modded" files will still be left behind and they instantly corrupt the game as you reinstall the game. what you have to do is uninstall the game and then go into your computer files and manually delete the leftover files. its a PITA to do this every time your game gets corrupted but you get used to doing it after a while.

uninstalling the game ONLY removes the original unmodified files so any file that was changed by adding a mod stays there until you go find it and delete it yourself, uninstallers are useless and don't work on those files. also if you forget to uninstall all mods before doing an uninstall and reinstall it can leave a huge number of files left behind