Categories articles do not display correctly

Hi.
I have this template running at victoriamiller.cl The front page and content pages look fine. However:
and category blog menu item displays with mistakes:

it does not display in 2 or more columns.
as you can see in this link, the list of articles is a real mess.
http://victoriamiller.cl/Pelando-Cables/

I have tried several settings /solutions to no avail. Please help. Thanks.

Any ideas on this? I really need to fix it. thanks.

Hi

This is clearly a validation error. You have an error in one of Your article. Please read the errors it may help You to track it: http://validator.w3.org/check?uri=http% ... ne&group=0