DATABASE TIPS: opiodr aborting process unknown ospid () as a result of ORA-28

I have been seeing the message opiodr aborting process unknown ospid () as a result of ORA-28 in the alert log of my 11g database daily and frequently. The message will be more frequent when there is a heavy load in the server.

I know that ORA-28 is a result of killing a session with alter session command
[oracle@dbtest ~]$ oerr ora 28
00028, 00000, "your session has been killed"
// *Cause: A privileged user has killed your session and you are no longer logged on to the database.

// *Action: Login again if you wish to continue working.

You can give me many ideas about this message opiodr aborting process unknown ospid () as a result of ORA-28 like,

This is an informational message only.

This is newly added to Oracle 11g.

This is introduced to ensure that all the processes are monitored in the database and captured alerts for unusual exit of any process.

But what if nobody is actually killing any sessions manually in the database?.

I got some useful information from the oracle support site. Here are the links to access them

"opiodr aborting process" Messages in Alert.Log