Oracle: Error for ORA-16014 and some basic commands

1. Cannot startup instance.
C:/>sqlplus /nolog
SQL> conn username/password as sysdba
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-16014: log 2 sequence# 1383 not archived, no available destinations
ORA-00312: online log 2 thread 1:
'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\REDO02.LOG'

SOLUTION:
SQL> alter database clear unarchived logfile group 2;
SQL> shutdown immediate
Then startup database: (In windows service or do command as follow)
SQL> startup mount

By the way, stop archive use this
SQL> ALTER SYSTEM ARCHIVE LOG STOP;
at 4/23/2008 11:17:00 AM