I had faced this problem because in my server_name.conf file in conf directory, I had changed these settings

<engine id=”rwEng” initEngine=”1″ maxEngine=”5″ minEngine=”2″ engLife=”300″

I had made minEngine to be greater than maxEngine

[2010/7/29 2:27:0:673] Exception 56081 (): minEngine must be smaller than maxEngine (4) and initEngine (1)

oracle.reports.RWException: IDL:oracle/reports/RWException:1.0
at oracle.reports.utility.Utility.newRWException(Utility.java:758)
at oracle.reports.server.EngineManager$EngineType.init(EngineManager.java:1858)
at oracle.reports.server.EngineManager.start(EngineManager.java:111)
at oracle.reports.server.RWServer.startServer(RWServer.java:789)
at oracle.reports.server.RWServer.run(RWServer.java:292)
at java.lang.Thread.run(Thread.java:534)
If you want to go in details of the problems, turn your trace on.