Continuous archiving fails routinely with "invalid magic number" error

I am having problems getting continuous archiving to work reliably on my
Postgres 8.3 system. My primary is running 8.3.1, has archiving turned on
and writes logs to a NFS mount that lives on the backup server. The warm
standby is running 8.3.3. Initially things work fine with the primary
copying logs to the archive directory correctly and the warm standby in
recovery mode plays them back okay. At some point the following appears in
the syslog:

May 26 08:58:37 ods2-prod postgres[3827]: [1424-1] LOG: restored log file
"00000001000000C2000000E3" from archive
May 26 08:58:51 ods2-prod postgres[3827]: [1425-1] LOG: restored log file
"00000001000000C2000000E4" from archive
May 26 08:58:52 ods2-prod postgres[3827]: [1426-1] LOG: restored log file
"00000001000000C2000000E5" from archive
May 26 08:58:55 ods2-prod postgres[3827]: [1427-1] LOG: invalid magic
number 0000 in log file 194, segment 229, offset 10780672
May 26 08:58:55 ods2-prod postgres[3827]: [1428-1] LOG: redo done at
C2/E5A45C80
May 26 08:58:55 ods2-prod postgres[3827]: [1429-1] LOG: last completed
transaction was at log time 2009-05-26 08:58:21.804665+00
May 26 08:58:56 ods2-prod postgres[3827]: [1430-1] LOG: restored log file
"00000001000000C2000000E5" from archive
May 26 08:59:11 ods2-prod postgres[3827]: [1431-1] LOG: selected new
timeline ID: 2
May 26 08:59:26 ods2-prod postgres[3827]: [1432-1] LOG: could not create
archive status file "pg_xlog/archive_status/00000002.history.ready": No such
file or directory
May 26 08:59:26 ods2-prod postgres[3827]: [1433-1] LOG: archive recovery
complete

I¹ve had this occur three times since setting up the warm standby. The log
file looks intact and I can¹t see any errors in the primary¹s syslog at the
time the log is generated and copied. There are no NFS or space issues
either on the backup server either. Can anyone suggest how to go about
diagnosing this problem?

Bruce