dba_jobs delay in execution, alert log shows stopping background process CJQO

HI,

I have recently upgrade from Oracle 10.1.0.5 to 11.1.0.6. After importing data from 10g to 11g.

We had 8 dba_jobs scheduled, a job which is scheduled to run every minutes waits for sometime to execute, which goes on a queue thus delaying other others to start executing. From the alert log, it shows Stopping background process CJO0, that stops the job. So I checked on the job that stops, On development server, I set the job queue processes to 20.. and created a replica of the same job. After that the alert log did not show the stopping of the background processes. As this happens in 2 other servers, i followed the same in stage(same parameter as set in dev) but the job