ORA-03113: end-of-file on communication channel

[oracle@our12test 11.1.0]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.1.0.7.0 - Production on Wed Dec 8 08:58:06 2010

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size                  2166536 bytes
Variable Size             427819256 bytes
Database Buffers          624951296 bytes
Redo Buffers               14000128 bytes
Database mounted.
ORA-03113: end-of-file on communication channel
Process ID: 16033
Session ID: 3000 Serial number: 5


SQL> shut abort
ORA-24324: service handle not initialized
ORA-01041: internal error. hostdef extension doesn't exist
SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64                                                                            

bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@our12test 11.1.0]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.1.0.7.0 - Production on Wed Dec 8 09:00:20 2010

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Connected.
SQL> shut abort
ORACLE instance shut down.
SQL> exit
Disconnected
[oracle@our12test 11.1.0]$ sqlplus "/as sysdba"
SQL*Plus: Release 11.1.0.7.0 - Production on Wed Dec 8 09:00:20 2010

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Connected.
SQL> shut abort
ORACLE instance shut down.
SQL> exit
Disconnected
[oracle@our12test 11.1.0]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.1.0.7.0 - Production on Wed Dec 8 09:00:35 2010

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> startup mount
ORACLE instance started.

Total System Global Area 1068937216 bytes
Fixed Size                  2166536 bytes
Variable Size             427819256 bytes
Database Buffers          624951296 bytes
Redo Buffers               14000128 bytes
Database mounted.
SQL> recover database;
Media recovery complete.
SQL> alter database open;

Database altered.

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64                                                                            

bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
[oracle@our12test 11.1.0]$ sqlplus "/as sysdba"

SQL*Plus: Release 11.1.0.7.0 - Production on Wed Dec 8 09:04:55 2010

Copyright (c) 1982, 2008, Oracle.  All rights reserved.


Connected to:
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> shut immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> exit

Then start normaly ...