I now get Gobbledy-gook at top of every page after upgrade from 1.2.5 to 1.5.1. This happens on every page of every blog and with the several different themes we use; it also happens on all admin pages. I tried turning off all plugins and widgets both site-wide and on each blog, but it didn't help.
The row of characters looks like this:
����������������������� ���&��� TEXT����������������������������
and appears at the beginning of the page source before <!DOCTYPE html PUBLIC ...
The only errors listed in server log have to do with some blogs not having terms related tables in database, but even blogs with the tables show the above problem.
Any help will be appreciated.