I am messing around with the grade book this afternoon. It is not as easy to work with as Microsoft Excel spreadsheets, so sometimes I have to deactivate, reactivate and rearrange various columns of the grade book.
To you guys, this'd look like rows moving up and down and disappearing in the My Grades page.
So do not panic. Everything is kosher. By tomorrow afternoon, it ought to look a bit more righteous.