Oracle reports engine hang on select and reports server get restarted by ompn

Hi,I'm using this configuration (oracle reports/forms 10.1.2.3 on AIX 6.1 TL07/power 7 64) and my problem is this : One of my reports enfine gets hang on a select query which take too long time (more then 10 min), then the reports server is restarted automatically by opmn. after the restart is complet some jobs can't be subbmited from oralce forms ( the windows become blanc).
I want to knew why opmn consider reports  in hang sutuation while the engine is just waiting the database to complet the execution query?
Why the engine which executing jobs with the long query not killed by reports server knowing that i have sit the engineResponseTimeOut to 10?