From the fine folks at ARBIME:
select U.user_name + '.' + T.table_name from sysobject O, systab T, sysuser U where T.object_id = O.object_id and U.user_id = T.creator and O.status = 2 /* Invalid */ and O.object_type = 2 /* views */
You can usually fix the invalid views by simply recompiling:
alter view MY_VIEW recompile
alter view MY_VIEW enable
You should review the changes made to any referenced tables/views to ensure that the invalid view doesn’t need to be rewritten.