What are ORA$AT_OS_OPT_SY_665 like 11g jobs?

Hi.

I'm having a problem with oracle 11g:
Once in a while system runs jobs named something like in a title.
Those are very resource intensive and in my case last for 4-5
minutes.
During this time my application using this db keeps getting errors on
trying to connect to a database or create a transaction.
Can anybody tell me what are those jobs and if I can do anything
about
it to stop it from blocking my server?

System parameters:
Oracle version: Oracle Database 11g Release 11.1.0.0.0 - Production
OS: Fedora release 8 (Werewolf), kernel: 2.6.23.1-42

Any help will be much appreciated.

Kuba
.

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