I have found using OpenLDAP 2.3.34 on a RHEL4 system (a locally built RPM) that the order of the overlays can lead to a problem (slapd locks up and doesn't do anything).
I have found that using syncprov, accesslog, auditlog, unique will work fine. But, adding refint to the end of that chain and then do a modrdn that triggers refint to want to change an attribute in another entry and your slapd is locked up. There is now one thread that will not end and you will only be able to shutdown slapd with a "kill -9".
However, if I change the order so that the refint is prior to the accesslog overlay, then it works.
Is this interaction between the two overlays and the importance of their relative order a known (or at least expected) -- or should I open an ITS?