Product theme background repeat problem

Hi all

I am a newbie and a noob when it comes to design. I'd thought I'd create a MU site using 3.0. Yes I know its not really supported yet.

When I try and get a background image to repeat, using the default css and uploading it to the media libary, it just repeats accross x and not a full repeat. No matter how many times I change the "Body background image repeat" to repeat, it just resets to repeat-x

Am I doing something wrong? Or is it WP3?

EDIT:- oh and "Insert your page navigation background image full url here" perminantly has repeat-x in it