alt131 - 10:48 am on Mar 6, 2012 (gmt 0)
Hi Ali and welcome to WebmasterWorld :)
Yes please to posting the css from firebug - we like code here and the sticky mail I sent gives more detail about why the original post was edited.
I think there is more going on than we have in the posted code. All elements are nicely centered for me, and while I think you are probably right that float will be causing problems there isn't one in the posted code - time to dig a bit more.
Have you validated the html and css? The reason I ask is that the posted code closes a <p> that isn't open. Loose ends happen when cut/pasting into posts, but sometimes the problem is in the original code as well. Odd open/closes crequires browsers to guess where to open/close elements and that can be the source of layout issues - which is another reason the code snippet may be performing differently to the complete document.