There is clearly something wrong with your installation of WordPress because no other clients are having this issue.
We are more than happy to find out what it could be, however, we need to have admin access so we can see what the configuration settings are. It will help us immensely to investigate the issue.
We will only go in and investigate, we will not make any changes without your permission.
Simply click “set as private reply” when responding to keep the admin user name and password private.