could not read transaction log directory ...?

Running some process on Postgres 7.3.2 I consistently end up with a crash.
This happens on Linux RedHat 6.2, kernel 2.2
Here's the fragment from the database log.

2003-05-07 14:38:48 LOG:  recycled transaction log file 0000000000000005
2003-05-07 14:48:56 LOG:  recycled transaction log file 0000000000000006
2003-05-07 15:04:10 LOG:  recycled transaction log file 0000000000000007
2003-05-07 15:04:10 PANIC:  could not read transaction log directory -
(<my_dir_path>/pg_xlog):Unknown error 523
 
2003-05-07 15:04:11 LOG:  server process (pid 449) was terminated by signal
6
2003-05-07 15:04:11 LOG:  terminating any other active server processes
2003-05-07 15:04:11 WARNING:  Message from PostgreSQL backend:       The Postmaster has informed me that some other
backend      died abnormally and possibly corrupted shared memory.       I have rolled back the current transaction and
am      going to terminate your database system connection and exit.       Please reconnect to the database system and
repeatyour query.
 
2003-05-07 15:04:11 WARNING:  Message from PostgreSQL backend:       The Postmaster has informed me that some other
backend      died abnormally and possibly corrupted shared memory.       I have rolled back the current transaction and
am      going to terminate your database system connection and exit.       Please reconnect to the database system and
repeatyour query.
 

The process is loading database with a large number of records,
it runs for about 20-30 minutes before it crashes.
Problem apparently originated in function MoveOfflineLogs (xlog.c)
At this point there are two files in the transaction log directory:
16777216 May  7 15:04 0000000000000008
16777216 May  7 14:55 0000000000000009

Does anyone have an idea why this could happen?

Thanks,
Mike.