LDAP Active Directory only works once

Hello All,

we have a strange problem with our SuiteCRM 7.8.2 and using LDAP.
It works well, but only once. As soon as the SuiteCRM-LDAP username and password are configured (credentials saved) through the Password Management only one time a user is able to logon succesfully. After that time the saved password of SuiteCRM-LDAP user is changed (even the dots shown are different).The password is changed as soon as only once a Active-Directory-user can succesfully logon. When we correct the password again another user is able to logon again, but only once. The suitecrm-logfile only registers the failed logon.
Mon Apr 24 14:03:38 2017 [18575][-none-][FATAL] SECURITY: User authentication for user.test failed
Mon Apr 24 14:03:38 2017 [18575][-none-][FATAL] FAILED LOGIN:attempts[1] - use.test

Kind regards,

Sander Vossen