Problems with Logon screen

We are in a CLM wave 9 Implementation project and we’re facing an issue when login to “fsbuyer”

We access the following URL http://<customer server>:50000/sourcing/fsbuyer/portal/login and access the standard login page:

In the standard login page, we complete user and pass and the system rise the following error

This behavior occurs randomly and after few attempts, we can login with the same user and pass that we couldn’t before. This occurs for every created user.

Find bellow our Directory configuration.

Any clue about this issue?

Regards,

Martin