ORA-00701: object necessary for warmstarting database cannot be altered.

Hello,

has anybody an idea how to solve the error ORA-00701: object necessary for warmstarting database cannot be altered????

SQL> ALTER INDEX sys.I_OBJ2 storage (maxextents 600);
ALTER INDEX sys.I_OBJ2 storage (maxextents 600)
*
ERROR at line 1:
ORA-00701: object necessary for warmstarting database cannot be altered

thanks

Werner