Database Software

Hi,

On my DB (XE, so I'm not sure to post in the appropriate forum), I've set 26 scheduler jobs (on my app account). They all have distinct frequency and/or repeat interval.
All theses jobs are PL/SQL jobs. They query some data though db link and insert results into local tables:
insert into local
select * from remote@dblink;

All is working fine but, from time to time, some jobs (not allways the same) are hanging. They appears in dba_scheduler_jobs as state = 'RUNNING'
I can not stop them without specifying "force".
There is no lock, nothing in alert.log
In dba_sheduler_job_logs, there is nothing, except some "Stop job with force called by user: 'XXX'" (of course, as I did stop force).

When running for a quite long time (many days), it happens taht 4 jobs are hanging. In this case, no more new job is submitted.

Please, let me know what should I check to understand why some jobs are not working, and if there is a workaround/solution.

Thanks for your help,

Leo.