I kept getting error messages like this:
ORA-01502: index 'SYSADM.PS_PSAESTMTDEFN' or partition of such index is in unusable state
I found the answer to the problem here:
As Katie mentioned in the comments, the status in 10g is UNUSABLE instead of INVALID.
Here is a quick script to rebuild all of the problem indexes:
declare begin for index_rec in (select owner, index_name from dba_INDEXES where status = 'UNUSABLE') loop execute immediate 'alter index ' || index_rec.owner || '.' || index_rec.index_name || ' rebuild'; end loop; end;