Need more details. Do you have a custom skin installed? Editor files? etc...
I've got editor files but its been fine for ages until now. And the career I'm currently playing isn't using the editor files
Any skins or pictures? Those are the usual causes for XML parsing errors. Try backing up and then removing anything in your install folder just to see if it makes a difference.
No skins or pictures. Tried backing up etc. and it still does the same thing. Could reinstalling the game help?