So I guess it's happening with the default theme as well (Site Admin -> Appearance -> Themes)?
- See if it happens with the default theme, too
- If you have plugins installed (you don't seem to, but just in case), de-activate them one by one at Site Admin -> Appearance -> Plugins and reload the site after every de-activated plugin
- If it works with the default theme, see if you have a blank space or blank line at the top or bottom of the file atahualpa3/functions.php
If it does not work with the default theme either: It seems that you're hosted at Dreamhost, I can only suggest to play around with the settings at "Manage Domains", try another PHP version, or ask Dreamhost, they may have had this problem before, with their 100,000 or so WP installations.
Since you probably installed via the auto installer I don't see what you could have done wrong with the Wordpress installation.