Alter or Drop a user throws error ORA-00600 [4842]

Alter or Drop a user throws error ORA-00600 [4842]

SQL> conn <usernam>/<pwd>   # ( user should be having DBA privileges )
Connected.
SQL> alter user SDEVKSTD identified by a;
alter user SDEVKSTD identified by a
*
ERROR at line 1:
ORA-00600: internal error code, arguments: [4842], [], [], [], [], [], [], []
 
Check  Alert.log
Mon Nov 17 12:30:45 2008
Errors in file /apps/oracle/admin/dotsoft/udump/dotsoft_ora_29220.trc:
ORA-00600: internal error code, arguments: [4842], [], [], [], [], [], [], []

SQL> SELECT PASSWORD FROM SYS.USER$ WHERE password is not null and name='<USERNAME>';
PASSWORD
------------------------------
APPLICATION

SQL> SELECT PASSWORD FROM SYS.USER$ WHERE password is not null and name='<USERNAME>';
PASSWORD
------------------------------
94528E67F6E7D2FF

$ sqlplus "/as sysdba"
SQL*Plus: Release 9.2.0.4.0 - Production on Mon Nov 17 14:15:24 2008
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
Connected to:
Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production

SQL> UPDATE SYS.USER$ SET PASSWORD='94528E67F6E7D2FF'  WHERE password is not null and name='<USERNAME>';
1 row updated.
SQL> commit;
Commit complete.

Now try altering the user 

SQL> alter user SDEVKSTD identified by SDEVKSTD;

User altered.