homepage sidebar lost format

I’m updating a website, and found a strange behaviour in home page.
Sidebar looks correctly in every page, but not in the dynamic front page: the widgets appear at the bottom of it, instead of appearing on the right side. This only happens in home page.
I’m using a child theme, but that trouble happens either I activate it or directly use twenty-ten.
Any ideas?
Here is the link:
http://www.hectorbraga.com
Many thanks
Val