Cannot Operate on User

Sir,

We found a new user with strange name '***', triple star which was created when the database was created, it have number of tables. We want to alter that user ie; we want to reset the password for that user. When we are trying to operate on that an error is returned.

SQL> alter user "***" identified by star;

Error at line 1:

ORA-00604: error occured at recursive SQL level 1

ORA-00001: unique constraint (SYS.I_USER1) violated

Details of the user is

USERNAME

USER_ID

PASSWORD

ACCOUNT_STATUS

LOCK_DATE

EXPIRY_DATE

DEFAULT_TABLESPACE

TEMPORARY_TABLESPACE

CREATED

PROFILE

INITIAL_RSRC_CONSUMER_GROUP