Contao backend login page keeps reappearing

[tinos]

Hi all

I have a problem on a new 3.0.3 installation. I am able login to the backend, but as soon as i click on any menu item on the left, it will bring me to the login-page again. Also tried on another machine and other browser.
Noticed a somewhat strange address with 3 slashes in address bar: mydomain///contao/main.php

any help appreciated
Tino

[Andreas]

You better don't use 3.0.3 it's outdated. I barely remember there was such a kind of bug. Use Contao 3.2.9 or 2.11.17.