iOS Web design issues

Hey guys,

I'm a web designer and I'm working on a site for my friends business.

The site looks fine on chrome, safari, IE 7/8 and firefox but when I open it on my iphone running 4.0.1, whatever part of the site that does not show on the screen when it loads is missing. In other words I can't scroll. If it is in portrait mode, I see more of it up and down but when I turn it to landscape, it gets wider to fill the screen but anything that flows off th ebottom is lost, if I try to scroll down, it gives me checker board and pops back up like there is nothing further below.

My site is fully tested to be W3C XHTML 1.0 and CSS 2.1 verified so I have used the clean standards that the industry likes but still nothing.

Any ideas?

I would prefer not to reveal the site quite yet as it is still int he works for the "client".

Thanks to anyone with info.