Look at the Control Panel, there under Region and Language settings, what does it state, is it correct?
look under the first two tabs...
Under Media Center there should be a menu item called OPTIONS (since I am using a non-english version I am not sure if it is really called OPTIONS) found under TASKS, there go to the DVD submenu, you should now find the Language Options, check there if they had gotten changed...
Post back if that helped or not...
Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."