Hmm...
I'm not sure what that exact security update is - I've never heard of it, so I'm thinking it's a German-specific update that we don't have here.
It may be affecting your browser's ability to accept "cookies," which are small bits of information about what you do at the Web sites you visit - like Log In information.
See if there is an option to allow our Website to use cookies for you. That may be the simple solution.
Let me know how it works for you.
~Addie~