ORA-01994: GRANT failed: password file missing or disabled.

SQL> GRANT SYSDBA to SYS;
GRANT SYSDBA to SYS
*
ERROR at line 1:
ORA-01994: GRANT failed: password file missing or disabled.

Solution: http://download.oracle.com/docs/cd/B28359_01/server.111/b28310/dba007.htm