Another report of the same bug: https://www.redhat.com/archives/spacewalk-list/2011-October/msg00067.html

To reproduce :
Monitoring -> Probe Suites -> [Select one] -> Systems

We receive an Internal Server Error- Catalina provides a query:

SELECT distinct s.id, s.name,
( SELECT  (CASE
                   MAX(CASE statps.state
                       WHEN 'OK' THEN 1
                       WHEN 'PENDING' THEN 2
                       WHEN 'UNKNOWN' THEN 3
                       WHEN 'WARNING' THEN 4
                       WHEN 'CRITICAL' THEN 5 END)
           WHEN 1 THEN 'OK'
           WHEN 2 THEN 'PENDING'
           WHEN 3 THEN 'UNKNOWN'
           WHEN 4 THEN 'WARNING'
           WHEN 5 THEN 'CRITICAL' END ) ST
           FROM  rhn_check_probe statcp
           LEFT JOIN rhn_probe_state statps
             ON s.id = statcp.host_id
          WHERE statcp.probe_id = statps.probe_id
          GROUP BY s.id ) status
FROM rhn_check_suites cs,
     rhn_check_suite_probe csp,
     rhn_service_probe_origins spo,
     rhn_check_probe cp,
     rhn_probe_state ps,
     rhnServer s
WHERE cs.recid = ?
  and csp.check_suite_id = cs.recid
  and spo.origin_probe_id = csp.probe_id
  and cp.probe_id = spo.service_probe_id
  and ps.probe_id = cp.probe_id
  and s.id = cp.host_id
com.redhat.rhn.common.db.WrappedSQLException: ORA-00904: "S"."ID":
invalid identifier

I found the query in the following resource:
java/code/src/com/redhat/rhn/common/db/datasource/xml/Monitoring_queries.xml

Fixed in spacewalk master by
commit 37f4aac214025b791e48c1df017113096d950570
    746090 - fixed join condition in query

Thank you Michael. When would one expect this to hit the nightly repo? Or maybe it could be had from Koji?

Got the latest RPM from nightly. This fixed the bug. Thanks again.

Spacewalk 1.6 has been released.