ldap_modify: Internal (implementation specific) error (80)

One of OpenLDAPs clearer error messages.  After much digging, it turns our this error (80) is generated when openldap does not  have enought locks.
On a side note, I came across an article in the the Zimbra wiki on performance tuning your ldap server.  Worth the read.  The tips in the article also solved the error 80.