Well, now I installed and activated Defensio for spam filtering.
It seems like the problem is with the Akismet API Key, my site can’t connect with akismet.com (that says the options page), but I didn’t change it and I’m using the same Api Key on another site and It’s working fine.
¿Any ideas?
Thanks Ipstenu.
I tried previously what you suggested, but I didn’t turned off ALL the plugins, I leave a few active, included Akismet.
Now, I turned off all the plugins and found that Akismet is causing the problem.
¿Do you know why is Akismet is doing this?