ORA-24005,ORA-00604 Errors while Dropping EXAMPLE Tablespace

SQL> drop tablespace example including contents;
drop tablespace example including contents
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-24005: Inappropriate utilities used to perform DDL on AQ table
IX.AQ$_STREAMS_QUEUE_TABLE_C

SQL> DROP USER IX cascade;

User dropped.

SQL> drop tablespace example including contents;

Tablespace dropped.