conflicts between newly created and previous LDAP/ODM - users disappear

We had troubles with our ODM where no new users could be created any more. We switched do standalone and tried setting up new ODM from scratch.
Everything was fine & ok first (DNS & Kerberos were ok, authentication was no problem). But suddenly we found that somehow the old LDAP db was interfering with the new one. Examples: I created some groups and users, some of both disappeard after a while in WGM, but were still there in dscl. Those were the exact users we had the same problems before with the previous install. Most of the groups show up twice in server admin, when setting permissions and acls for the shares - one of the entries always showing gid number from the older ODM and these ones don't show up in WGM as well.

My users (and I) are very frustrated about permanent file sharing and log in issues. So I am considering to once again rebuild ODM from scratch. But this time, I'd like to see if there is a way to completely purge any existing older entries anywhere on the system that could interfere with the new configuration.

Does anybody know how to do this?

Thanks,
Hakan