All pages go blank if page content is not assigned to a column

I am using PE, on D7.23 with an Omega4 subtheme.

While changing the site default layout to a 3 column layout, I did not see and did not assign the "site content" section to any column. As soon as I hit save, the page went white. And actually all the pages have gone white (it's hard to say since, I can only get URL's in from browser memory because... well, all the pages are 100% white).

This is what happened to the best of my recollection, it happened quickly. But I am pretty sure that the site content section (or whatever it's called) was not assigned to any of the columns. The upshot is, that if the site content is not assigned to any column/section in the layout, the site is essentially gone. When I view source, there is markup, but the browser shows 100% white.

Seems there should be some sort of validation ensuring that the output of the site is somehow ensured to be assigned to some visible column.