One of the forum users, DEAK, had find the solution.
Hi,
I've had a look at the site. I think this is an issue with NeoGallery; either its template or associated CSS. Specifically, I think the problem starts somewhere around:
I've never used NeoGallery myself, so I'm not sure how it works. However, if you can get to the template of it, perhaps try removing the "clear" from the above DIV's class.
As an alternative, perhaps try using a different photo gallery just to test if the problem remains -- for example, maybe NeoGallery's stylesheet/template do not work great with your site. Maybe they need some tweaking, I'm not sure. Or try posting in the Modules forum, because this problem looks to be module specific rather than a more general layout problem.
By the way, I looked at the site in Google Chrome and the problem is much worse.
Hope that helps a little.
I removed the Clear from and the problem was solved.
Many thanks to Deak!