When creating new site on a multisite, success page doesn't load.

When somebody opens a new site on my multisite it freezes after the site is created and doesn't load the "Congratulations! You have successfully registered a new site." text. It just shows a blank page.

You must login to my site http://www.sneakheads.com then visit the following link to create a site.

http://www.sneakheads.com/stores/create/