I've just tried to do a copper-pour on a board I'm nearly done with, for some reason it doesn't "pour" and only leaves an outline of where the pour tool selected, I also get a dialog saying it didn't pour because of board cutouts, keepouts, or "other" objects, as far as I know ...I don't have any keepouts/cutouts or other objects.

Here are the screen shots of trying to do a pour:

First the selection area



then the (error?) dialog



then the result



so what am I doing wrong here?

Probably you have board cutout instead of board outline. Copper pours can't be poured inside of board cutout.

How can I tell?

Tell what?
Remove the board cutout and draw board outline. Click on "Place board outline" button, then define points on design area and press enter.

Well, my question was, when I have a "board outline" on the board ouline layer, how do I tell if it's not a board outline?

Removing what I have and making a new one doesnt answer the question really.
(but thank you BTW)

If you right click the purple shape, if in the popup menu it starts with "insert point" and end with "board point", then it's a board outline, otherwise if you select the shape, you will see that "type" is board cutout in the properties panel.

Thank you.