Sidebar interfering with gallery display in firefox

[keress]

I have a page displaying a dynamically generated photo gallery (in Wordpress site). It's fine in IE, but in Firefox, the presence of an unordered list in the sidebar causes a gap in the rows of photos.

http://www.galaxyplastic.com/?page_id=167

The stylesheet is at

http://www.galaxyplastic.com/wp-cont...laxy/style.css

The same problem occurs on a different site with different server, using the same sort of stylehsheet.

Any suggestions on what I can try will be greatly appreciated.

Thanks