Have in mind that there are many harmless locks that might exists for more than 30', row exculsive on SYS._NEXT_OBJECT, etc.

Use this statement to find the locks:

Code:
select nvl(S.USERNAME,'Internal') username,
 nvl(S.TERMINAL,'None') terminal,
 L.SID||','||S.SERIAL# Kill,
 U1.NAME||'.'||substr(T1.NAME,1,20) tab,
 decode(L.LMODE,1,'No Lock',
  2,'Row Share',
  3,'Row Exclusive',
  4,'Share',
  5,'Share Row Exclusive',
  6,'Exclusive',null) lmode,
 decode(L.REQUEST,1,'No Lock',
  2,'Row Share',
  3,'Row Exclusive',
  4,'Share',
  5,'Share Row Exclusive',
  6,'Exclusive',null) request
from V$LOCK L,
 V$SESSION S,
 SYS.USER$ U1,
 SYS.OBJ$ T1
where L.SID = S.SID
and T1.OBJ# = decode(L.ID2,0,L.ID1,L.ID2)
and U1.USER# = T1.OWNER#
and S.TYPE != 'BACKGROUND'
order by 1,2,5;
Then populate the table with the data and check for same locks in the table. If such exist, email the info.