What's the problem?
There are a couple MOS notes on a bug related to SMCO, some indicate trouble when a tablespace is trying to autogrow.
Are there any datafiles with .... AUTOEXTEND ON NEXT ... ?
There are also a few mentions of troubles with tables or indexes having a very small .... NEXT .... parameter.
select OWNER, INDEX_NAME, NEXT_EXTENT from dba_indexes order by NEXT_EXTENT desc
select OWNER, table_NAME, NEXT_EXTENT from dba_tables order by NEXT_EXTENT desc
One must know the problem before trying to fix it.