POSSIBLE SOLUTION: Verify that the database was shutdown cleanly by doing the following:
1. Verify that following files do not exist
If these file exists, remove them.
2. Verify that there are no background processes owned by "oracle"
% ps -ef | grep ora_ | grep $ORACLE_SID
If background processes exist, remove them by using the Unix command "kill". For example:
% kill -9 <Process_ID_Number>
3. Startup the instance
If you do not have any other database running on this server then you can also try :-
3. Verify that no shared memory segments and semaphores that are owned by "oracle" still exist
If there are shared memory segments and semaphores owned by "oracle", remove the shared memory segments
ipcrm -m <Shared_Memory_ID_Number>
and remove the semaphores
ipcrm -s <Semaphore_ID_Number>