Might sound silly, but try to reinstall the game, by uninstalling it, then deleting the folder and reinstall (fixed it for another guy with smiliar issues). i dont know enought about where the game puts files. but i figure trying to delete the catch(temporarly files) from the updater might work too.
edit: gah noticed you already tried reinstalling, you mate sure to delete the game folder too right? so it didnt keep any files from your previous install
"Orks is never beaten in battle, if we wins we wins, if we die we die so it don't count as beat, an' if we runs for it we don't die neither, so we can always come back for another go!"