I too, have just recently found out that I've been banned from commenting in the MSN news section. I hardly ever use MSN anyway, and I've never posted anything on there, as far as I know, so I can't imagine what it would be for. When I look at my activity page and comment history, it is blank. So, again, just like all of you, I wonder ... WHY?
I really don't care if I'm banned from commenting on the news (I just won't read it anymore - lol), but my account better not be banned from sending/receiving emails. THAT would make me very upset. Also, I have no other Microsoft products, i.e. X-box, nor any online subscriptions, but if I had something like that I had to pay money for and got banned, that would be grounds for a lawsuit and a complaint with the FTC.
My guess is that mine is a mistake. The only problem is trying to contact someone from Microsoft Guidelines Dept. to once again, ask why? Where do we send emails when we have a problem?