I don't know if this has anything to with anything, but when I read your post I went looking through my internet options.

When I got to Programs, I notice there is an html editor. When I click on the drop down menu, it just shows notepad. I don't have any other word processing programs. But my thought is....maybe if its directed to use Word or some other program with a spell check, it'll use that for forums and blogs? I don't know though....just a thought and the only thing I could find.