ORA-04063 table has errors

Hello,
I'm new to oracle and have problems with it....
I don't know when it happened, but i have problems with the main instance of my database wich is being terminated and then restarted every 4-5 minutes.
In the log files there is :

Error 4063 in Queue Table QS.QS_ORDERS_SQTAB
kwqitmmsgs: error 604
error 604 detected in background process
OPIRIP: Uncaught error 447. Error stack:
ORA-00447: fatal error in background process
ORA-00604: error occurred at recursive SQL level 1
ORA-04063: table "QS.QS_ORDERS_SQTAB" has errors

The user QS and his tables belong to the tablespace EXAMPLE wich is installed with ORACLE. I tried to delete the table, the user, the tablespace.... none of these is possible : each time i get the message "End of file on communication pipe" or so error (i don't know the correct translation of the french message : fin de fichier sur le canal de communication).

So if you have any idea, let me know....
THANKS

There's some patch scripts available on metalink for this ...
http://metalink.oracle.com/metalink/...&p_id=231074.1