Thank you very much.
We checked as admin and as logged out user.
Since it is a live page we are not able to make a plugin conflict test, now.
Our solution is to use a plugin for password protection, now:
Password Protect WordPress Lite
So now it works as expected.
Thank you very much.
sorry guys.
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
helps.
closed.
