Deactivate all GeoDirectory dependent add-ons first before deactivating GeoDirectory.
When activating GD, this message comes up:
The plugin generated 3 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.
I have no idea where that comes from. I have never seen that before like that, so I guess that comes from the theme.
The only error I can find is that when you save some settings, rather than re-loading the page, you get a blank page. Just using the back key takes you back to the saved pages then.
Follow the links at the login page:
https://codex.wordpress.org/FAQ_Troubleshooting#How_do_I_solve_the_Headers_already_sent_warning_problem.3F
Check your config file or switch to a simple theme to see if the problem is somewhere in the theme.