Oracle Database Discussions

My database is working in very strange way

SQL> Select * from DBA_USERS;
Select * from DBA_USERS
*
ERROR at line 1:
ORA-00942: table or view does not exist

Is this possible?
DB version : 9.0.1.1.1
I am connected as sys as sysdba.

And if I do a select from dictionary for this view; it exists in the dictionary.

SQL> Select * from dict where table_name like 'DBA_US%';

TABLE_NAME
------------------------------
COMMENTS
---------------------------------------------------------

DBA_USERS
Information about all users of the database

DBA_USTATS
All statistics collected on either tables or indexes


What is wrong?