Customize.php not showing anything

Hi,

Just finished installing WP. Downloaded the latest version.
Tried installing, and got a small error: I entered the right credentials and database name however a correct wp-config.php was not written. I entered user/pass/dbname/server myself. After that the 5-min installation fired up just fine.

However when I want to customize anything (Appearance–>customize) the customize page is not showing up on the right like all the other options. It takes me to a page where I have only a few options to configure like site title & tagline, colors and some image stuff.
But nothing happens when I click on the menu. I cannot change the site title, colors or anything else. NOTHING! Tried downloading some custom theme and same results.

Anyone have had this problem ?
Thanks a bunch!