Horizontal DIV Scroll: Safari vs iPhone

I need some help ASAP!

I coded a very basic website with a horizontal scroll. It works beautifully on Safari, Chrome, Firefox, etc. But for some reason, I can't scroll past about 1400px on any give page in the site with my iPhone, at which point, the browser simply cuts off the last image. In fact, the scroll bar doesn't even appear on the iPhone. And it drops one of my navigation images to the line below it (which has nothing really to do with the scroll problem, just also buggy).

I looked through my CSS files to make sure I had not specified a fixed width as well; no luck. I don't want to use Flash, obviously, because the purpose of the site is to be simple and accessible from a smart phone.

This is the code I used:

div class="scroll"
img src="../images/wishbone_logo.jpg"
img src="../images/wishbone_plate.jpg"
img src="../images/wishbone cuttingboard.jpg"
img src="../images/wishbone_placemat.jpg"
/div

Can anyone help?! I need to get this figured out so that I can use the same code for a client's website.

Thanks!