ORA-01033: ORACLE initialization or shutdown in progress

Problem
While connecting to database user get the error,
ORA-01033: ORACLE initialization or shutdown in progress

Cause of The Problem
SYSDBA used issued STARTUP command to the database and while starting up database, connecting to database as normal user will get the error ORA-01033.

There may be the scenario that SHUTDOWN command waits a long time.
Solution of The Problem
Scenario 01:
Based on the situation STARTUP may take fewer minutes. As a normal user what more you do is to wait few minutes and try again. You will succeed if database is open state.

Here is the waiting result.
C:\Documents and Settings\Queen>sqlplus nikunj/a

SQL*Plus: Release 10.2.0.1.0 - Production on Fri Mar 21 15:34:23 2011
Copyright (c) 1982, 2005, Oracle. All rights reserved.

ERROR:
ORA-01033: ORACLE initialization or shutdown in progress


Enter user-name: nikunjdw
Enter password: *****
ERROR:
ORA-01033: ORACLE initialization or shutdown in progress
Enter user-name: nikunjdw
Enter password: *****

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options

At third attempt I became succeed.

Scenario 02:
If you have SYSDBA privilege then connect to database as SYSDBA and see the status of the database.
SQL> conn / as sysdba
Connected.
SQL> select open_mode from v$database;
select open_mode from v$database
*
ERROR at line 1:
ORA-01507: database not mounted

SQL> select open_mode from v$database;
select open_mode from v$database
*
ERROR at line 1:
ORA-01507: database not mounted

SQL> select open_mode from v$database;

OPEN_MODE
----------
MOUNTED

SQL> select open_mode from v$database;

OPEN_MODE
----------
MOUNTED

SQL> select open_mode from v$database;

OPEN_MODE
----------
READ WRITE

As we can see that database gradually became in usable state. Someone issued STARTUP command and it took some time to be in READ WRITE state.

Scenario 03:
If shutdown takes more time suppose SHUTDOWN NORMAL.... then issue,
SHUTDOWN ABORT;
and later normal startup,