I don't think that's why your login isnt working, are you sure that wasnt there before? I've seen that error in Pentaho 8 CE vanilla install.. Ignored it, all seems fine.
Try enabling the debug ldap logging, restart the server and see what it shows you..
Enabling Verbose LDAP Logging - BI Platform - Pentaho Wiki
Also check out this blog:
Diethard Steiner On Business Intelligence