cb login required - how other component can use this login

We are doing the upgrade to Joomla 3.4 with the CB and an other component 'osg seminarmanager'.
This other component is using the standard Joomla login function and was working fine under Joomla 2.5.

With Joomla 3.0 we also had to update the CB and we had to use the new CB login instead of the standard Joomla login.

But now I have problems with the login process.
How should it work with the new necessary CB login and other Joomla components which also use a login functionality?

I checked this forum. We have CB 2.0.9. The CB system plugin is the third system plugin after system-admin tools and system-admin exile.
All joomla module are unpublished. We use only cb login module with the setting 'encrypt login module' is yes. The url is fine, mod-rewrite is on.

You can have a look on a test installation - www.es-rm-eltern.eu/ev341/en/afternoon-activities/5-nachmittags-afternoon/199-ballschule141215142144?buchung=1

Scroll down a little bit and see the field 'username' and 'password'. Type in any words and you will see that the system jumps to the cb login page without any usage of the entries before. This happens also with valid users.

Thank you so much for your help.

Kind regards.

By default CB will redirect Joomla login URLs to CB login URLs. This is controlled by "System - Community Builder". It can also rewrite those URLs if enabled in its parameters. This should cause all those login URLs, forms, and redirects to point to CB instead of Joomla. I can't guarantee this will be compatible with all 3rd party extensions, sorry. I recommend disabling all 3rd party login/registration functionality when possible.

Thanks for your fast answer.
This will help to find a workaround for 3rd party component.