@mike - I turned on the wp_debug.
I am not sure how to turn off any caching systems? If it is a plugin - I do not have any caching plugins installed.
I tried to debug using the guide you provided, but I must confess this goes way over my head :-( . But wp_debug is active and the link to my site is Mom Goes Online
I re-activated the genesis 1.9.1 child theme (magazine 2.0) as this is when the error occurs. (it does not happen with the standard wordpress 2012 theme).
From the studiopress forum I deduct that others have successfully installed wordpress 3.5, a genesis 1.9.1 child theme and the Wordpress SEO - and it all works fine. Since I have no plugins installed aside from Wordpress SEO, the suggestion was made that it could be due to a server set-up.
I have no idea what that means or how I can find that error, but this is how I installed Wordpress 3.5
1) I use Westhost (based on Yoast's recommendation :-)
2) I used the softaculous button