Originally Posted by juggledad
go to the ato-> export/import settings and press the button labeled 'delete bfa_ata4'
ato = Atahualpa Theme Options
The button is at the bottom of that page of options
The same thing happened to me, just a blank screen after updating to 3.5.3. I submitted a ticket to my host (Fatcow) and they bumped up the request to a higher level support who decreed, the problem was in the template and reverted my site back to the basic WP template. I decided to check the forum to see if this was a problem, and here was the fix. It worked and now I am back to version 3.5.3. Thanks.