Ok will try and explain.
Go into admin cpanel and clcik on log out or can do same from nav bar in the photopost main gallery page.
When click on log out I go to mydomain/photopost/index.php
This gives me a login page and when I enter my user name and pasword I go to mydomain/photopost/login.php and get a page not found error. I ahve no login.php in photopost directory it is looking for.
My site Here
Use the logout in the nav bar in the photopost gallery and it will do the same.
Log out and get the page all cookies cleared and then clcik on return to previous page.
Enter user name and pass test and test and it will take you to Not found Page with mydomain/photopost/login.php in address bar.
It is being directed to the wrong place to log back in from photopost.
I can go to my homepage and login to get back to the PP gallery.
I can give admin acces if you need to get into cpanel.