These are completely wild guesses, just stalling and bumping the thread until someone knowledgeable comes along.
Are there any underscore plugins in the plugin directory? What if you put an underscore plugin in that folder, if there are none now?
Is it possible
glob is disabled in your php.ini, and the conditional in this file is not working properly when
glob is disabled (create a phpinfo file and look for the disabled_functions section to see if glob is there.
That’s all I’ve got right now