Nobody is putting messages in your computer but you.
This is a "Newsgroup" - it's like a bulletin board, on tens of thousands of
computers worldwide. You are evidently using Outlook Express and have chosen
to use the "News" feature. If you don't want to see the messages in
microsoft.public.access, unsubscribe from the newsgroup. See the Help for
"newsgroup", "subscribe" and "unsubscribe" if you don't know how.