how to edit tiffs without zuking up the alpha

[Dave Morse]

Hi,
I've got tiffs created in Photoshop that I need to crop using Gimp.  They
have alpha.  If I open the up in Gimp, use the crop tool, then resave, the
next time I open them I discover that only the alpha-mask has been saved
in place of the rgb data.

before save:  http://24.16.52.60/~dm/before.tif
after save:   http://24.16.52.60/~dm/after.tif

Needless to say, this is not what I want.

How do I do what I want?

(Please CC me on replies, as I don't subscribe to gimp-user)