Michele,
I had set the OOoFigure style in the draft OOo3 template to "keep with
next paragraph" (on the Text Flow tab of the paragraph style dialog)
when we were testing having the caption in the following paragraph
instead of within the same frame as the picture.
If we have decided to go back to using figs+captions in a frame,
you'll need to be sure to change that setting for the template -- or
some figures that actually do fit in the space at the bottom of a page
or column will jump to the next column or page.
Cheers, Jean