I had a client experience this issue, and Kiwi's suggestion about Customizing the Area Page and unmarking the phantom section resolve the problem, at least for now. Just be sure to also switch to another Area Page before attempting to exit GP. Until we did that, the problem persisted.
It is also nice to have the SQL script in my back pocket, in case it recurs before I can get them service-packed. (Although I do not have confirmation that it was one of the fixes in that SP.)
Thanks for your posts, everyone!