Try flicking between the messages at the bottom then close. It should stop reappearing and I remember similar problems in the past, always associated with news items without an active link if I recall correctly.
Same here. over and over again. Trying to write a message and it kept popping up over the text there. And a few other places too. I did manage to clear the problem in the end by completely rebooting the laptop.
If you look at the second panel at the bottom of the News box, you will see a small, red 'NEW!' tag. This is an item that has not been read, and will cause the News window to pop up with every screen change, but it will pop up to the first panel.