Pemalinks settings

I’m having a little (or big) problem and after reading many many websites, and google a lot still can’t solve it.

The problem is that my homepage isn’t working if i select the “Post name” setting. Everything else works fine.

Take a look here: http://www.ClasificadosValleMedio.com — as you’ll see, it doesn’t work

it should look like: http://www.ClasificadosValleMedio.com/inicio — inicio is my homepage

The problem started after i changed the URL of my website (Settings->General-> Site URL/URL), i was using a subdomain (something like clasificados.example.com) and i changed it to clasificadosvallemedio.com, however i didn’t moved any file nor anything.

Thanks in advance!