ERROR: could not access status of transaction 283479860

We started getting the following error on some transactions on our database
(when against particular rows run against the table).

PGError: ERROR: could not access status of transaction 283479860 DETAIL:
Could not open file "pg_multixact/members/4D6D": No such file or directory.

We don't know what happen or how to recover. Any advise?

We are running
PostgreSQL 9.3.5 on x86_64-unknown-linux-gnu, compiled by gcc
(Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3, 64-bit

pg_controldata .

pg_control version number: 937
Catalog version number: 201306121
Database system identifier: 6049974226855122843
Database cluster state: in production
pg_control last modified: Wed 01 Apr 2015 05:53:33 PM EDT
Latest checkpoint location: 6D77/6D729948
Prior checkpoint location: 6D77/6BBC9038
Latest checkpoint's REDO location: 6D77/6BE0F0E0
Latest checkpoint's REDO WAL file: 0000000100006D770000006B
Latest checkpoint's TimeLineID: 1
Latest checkpoint's PrevTimeLineID: 1
Latest checkpoint's full_page_writes: on
Latest checkpoint's NextXID: 0/2713180814
Latest checkpoint's NextOID: 1709773115
Latest checkpoint's NextMultiXactId: 318596530
Latest checkpoint's NextMultiOffset: 2059555326
Latest checkpoint's oldestXID: 1746597315
Latest checkpoint's oldestXID's DB: 16415
Latest checkpoint's oldestActiveXID: 2713180814
Latest checkpoint's oldestMultiXid: 54760341
Latest checkpoint's oldestMulti's DB: 16415
Time of latest checkpoint: Wed 01 Apr 2015 05:50:01 PM EDT
Fake LSN counter for unlogged rels: 0/1
Minimum recovery ending location: 0/0
Min recovery ending loc's timeline: 0
Backup start location: 0/0
Backup end location: 0/0
End-of-backup record required: no
Current wal_level setting: hot_standby
Current max_connections setting: 600
Current max_prepared_xacts setting: 0
Current max_locks_per_xact setting: 64
Maximum data alignment: 8
Database block size: 8192
Blocks per segment of large relation: 131072
WAL block size: 8192
Bytes per WAL segment: 16777216
Maximum length of identifiers: 64
Maximum columns in an index: 32
Maximum size of a TOAST chunk: 1996
Date/time type storage: 64-bit integers
Float4 argument passing: by value
Float8 argument passing: by value
Data page checksum version: 0

--
Thank You,
Pweaver (pweaver(at)panjiva(dot)com)