posted grades are hidden again

[kmcgrath]

I have manually released the grades for my first few assignments three times now, and when I go back in, they're hidden again.  I know that the students can see them briefly, as I've received some comments back, but then someone else emails to tell me they can't see their score.  My posting policy is set so all grades are hidden until I release them, but they're not staying released!  Anyone else having this problem?