No it breaks in Mozilla Firebird. I think you already knew you had problems there.
Download Firefox the new version of Moz http://www.mozilla.org/products/firefox/ and you can see the problems.
You can also get Netscape here http://channels.netscape.com/ns/browsers/download.jsp
and Opera here http://www.opera.com/download/
I did test my website in Mozilla. I am aware of the problem with the slide menu on the left.
I don't really understand what you mean with "breaks"??
Do you know why between the form fields at the bottom of the page dark vertical stripes appear?
Breaks - Well with the left menu covering one third of the page, then it is broken in Moz, does not work correctly, to the point where required data/information the viewer wants is not there.
On you other problem - I would say it is something to do with the CSS. Try removing
vertical-align:top; and float:left; and clear: both; from #contentfooter. They are not required. If the two input forms do align themselves togther just use a <br /> to force the second one down.