Ok, now we've got a different issue. Apparently he's special and didn't try that dropdown box *facepalm* so now the config is in english now. But he still has the issue which was part of the reason I made him reinstall in the first place...
Whenever he tries to change and of the options in the config, he gets an error report. So he's not able to switch things (like going from fullscreen to windowed mode for example). Anybody have any idea how to fix that?
EDIT: Nevermind! I was able to google up a fix. His game is working now and he can finally play again!
Thank you for all the help and suggestions you all gave while we were going through this!