@Jayesh. Thanks. To re-iterate. DB2 Version is db2 v8.1FP 7a on AIX
5.3.
There is nothing written to the db2diag.log or the notification log at
the time of the error. However, previous REORG failures did leave some
.OLR files in the database data folder (presumably containing data
about the online REORG status of the respective table). When I remove
these, the REORG command works fine.

@Michel. Thanks, that was helpful. I cannot find column descriptions
for the output of the db2 "select * from TABLE
(SNAPSHOT_TBREORG('AUTOM02',-1)) as A" command. Can you point me to any
documentation which provides descriptions for these columns (i.e.
REORG_STATUS, REORG_PHASE etc.)?