Archive WAL Logs Failed

Hi All,

Yesterday, we'd archiver problems in copying archived wal files from
pg_xlog to archive destination at the end of full hotbackup. Below are
the errors from server logs.
What makes me to wonder is that why does archiver tries to copy
"000000010000000800000074.0066C9C0.backup" again when it's already been
archived. As soon I removed "000000010000000800000074.0066C9C0.backup"
from archive location, then archiver was happy to copy again and moved
on to archiving 000000010000000800000074 etc.

2006-11-07 00:35:23 CST LOG: archived transaction log file
"000000010000000800000074.0066C9C0.backup"
2006-11-07 00:35:23 CST LOG: archive command "test ! -f
/b01/pgdata/archive/db1/000000010000000800000074.0066C9C0.backup && cp
pg_xlog/000000010000000800000074.0066C9C0.backup
/b01/pgdata/archive/db1/000000010000000800000074.0066C9C0.backup"
failed: return code 256

Any idea what may be going on here.

Thanks,
Stalin

PG814, RH4.0