Hi found the problem,
Seems that there is a bug of "System - 2JToolBox Plugin" plugin.
You can make a simple test: disable or remove Easy Profile (not important) and try to edit article from backend, you will get a blank page
and this is due to "System - 2JToolBox Plugin" plugin
With Easy Profile you have problem in frontend because plugin "System - 2JToolBox Plugin" and "Easy Profile - Author" plugin try to edit author information: I don't know what 2jtoolbox do but easy profile author plugin simply add avatar and link to user page (Easy Profile author plugin is not necessary to work with Easy Profile)
You can disable Easy Profile author plugin and frontend should work, but anyway you always have a error in backend due to "System - 2JToolBox Plugin" plugin (with or without Easy Profile and all our plugins)
Now I have enabled all Easy Profile plugins except "Easy Profile - Author plugin" and now frontend works, but you still have a problem in backend.