duplicate key value violates unique constraint "pg_class_relname_nsp_index"

HI,

Following error is continuously seen with the postgreSQL database which we are using at customer site.

Current Errors observed: ./fm_db_VoiceReprocessing1/data/pg_log/postgresql-04.log:2015-04-04 01:00:16 CESTERROR: duplicate key value violates unique constraint "pg_class_relname_nsp_index"

Any pointers on why these errors are coming? What is the meaning of duplicate key value violates unique constraint "pg_class_relname_nsp_index"
If it is due to some index corruption or duplicate index? Please help.

Following tables are used frequently in our case

CREATE TABLE AuditTrailLogEntry
(
event int2,
inNodeID VARCHAR(80),
inNodeName VARCHAR(80),
sourceID VARCHAR(300),
inTime TIMESTAMP, -- YYYY/MM/DD HH:MM:SS.mmm
outNodeID VARCHAR(80),
outNodeName VARCHAR(80),
destinationID VARCHAR(300),
outTime TIMESTAMP, -- YYYY/MM/DD HH:MM:SS.mmm
bytes bigint,
cdrs bigint,
tableIndex bigint, -- Unique key
noOfSubfilesInFile bigint,
recordSequenceNumberList VARCHAR(1000),
primary key (tableindex)
) TABLESPACE MMDATA; -

CREATE TABLE EventLogEntry
(
tableIndex int4, -- Unique key
object VARCHAR(80),
method VARCHAR(80),
bgwUser VARCHAR(80),
time CHAR(23), -- YYYY/MM/DD HH:MM:SS.mmm
realUser VARCHAR(80),
host VARCHAR(80),
application VARCHAR(80)
) TABLESPACE MMDATA;

Regards
Mitu