I dunno about your specific issue, but maybe this will give you something to go by. Yesterday I got a call froma client that there spellcheck would challenge everything no written in French, I haven't found the problem yet, but I woke up to another email about close to the same thing, only it's system wide.
I would ask you as I have them, do you use outlook, and is this problem persisting there as well ? The one persons issue is system wide, the others is just in word , and outlook.
Interesting. I'm looking for a correlation between yours and there's.