Same here — admin functions went dead. I deleted the new version (through ftp) and replaced it with a backup I had from a couple weeks ago. The admin functions now worked again.
Then I tried again to upgrade in case it was a fluke — same issue. When I went back into my ftp to delete and replace with the old version of Statcounter, there was now a new plugin that I had NEVER installed before: mr_links_widget.php — I backed up that file, but deleted it from my plugins. What the heck is going on? Anyway, I replaced the plugins as they were and everything is working now.