Text box layout settings are changed when the document is closed

I have a text box in my footer. I have set layout settings for it so that it
displays in the right place. The wrapping style is Square, the horizontal is
aligned right relative to column, the vertical is absolute position .47"
below Bottom Margin, and the Options are Allow overlap and Layout in table
cell. (Some of these may be irrelevant to the problem, but I'm not sure
which.)

After saving the document, when I close the file and reopen it, the
horizontal and vertical layout settings are changed - horizontal to an
absolute position to the right of Page and vertical to the same absolute
position but below Page. This ends up moving my text box into the header.

This is in Word 2007. Does anyone know why the layout settings are being
changed?

Thanks.