I've got a strange wrapping effect appearing only in Mac Firefox 3.5.

the images seem to wrap under each other under some of the rows. Here's an example page:
http://www.artefactdesignsalvage.com/products-page

I've expanded the items class:
.scrollable .items {
/* this cannot be too large */
width:800000em;
position:absolute;
clear:both;
}
But it doesn't change anything.

The wrapping disappears on refresh.

Any ideas?