bdb_index_read: failed

[Arwin <arwin@infopact.nl>]

Hi all,

We are running 1 master server and a couple of slaves, all openldap-2.4 on Ubuntu 8.04 lts, syncrepl 
and cn=config configuration.
The last couple of days we are getting a few of the following errors in the slapd logs:

Apr 29 11:03:41 ldapsrvr-1 slapd[6112]: bdb_idl_fetch_key: [b49d1940]
Apr 29 11:03:41 ldapsrvr-1 slapd[6112]: <= bdb_index_read: failed (-30990)
Apr 29 11:03:41 ldapsrvr-1 slapd[6112]: <= bdb_equality_candidates: id=0, first=0, last=0
Apr 29 11:03:41 ldapsrvr-1 slapd[6112]: => bdb_equality_candidates (objectClass)

Tried solving it by re-adding the index and running slapindex but the errors still remain.

Everything seems to work ok though, replication works, we can add/edit entries and user 
authentication of accounts in the dit work just fine.

Can anybody tell me if this (bdb_index_read: failed (-30990)) is something that needs to be fixed 
and if so, how?

T.i.a.

Arwin.