Problem with a query

Hi everyone! I'm getting an error with this query:

Code:

---

select * from
(
        select
                avg(esiti.num_record) as media, count(*) as num_esiti
        from
                c_esiti esiti
        inner join
                (
                        select
                                distinct dt_rif
                        from
                                c_esiti es
                        where
                                es.r_id_controllo = @id
                                and es.fl_successo = 1
                                and es.dt_rif <>
                                (
                                        select max(esi.dt_rif) from c_esiti esi
                                        where esi.fl_successo = 1 and esi.r_id_controllo = @id
                                )
                ) esiti_ok
        on
                esiti.dt_rif = esiti_ok.dt_rif
                and esiti.dt_elab =
                (
                        select
                                max(dt_elab)
                        from
                                c_esiti e
                        where
                                e.dt_rif = esiti_ok.dt_rif
                )
) esiti_precedenti

---

The funny thing is that the inner query (the one that produces "esiti_precedenti") works fine, but when I try to use it as a subquery I get "Internal SQL Server Error". The query produces a single row with an average and a count; I would need to append these two values to a row I get from another query, so my approach was to join them "on 1=1". Can you suggest an alternate way of doing it?

I'm using SQL Server 2000 in Query Analyzer.

Nevermind, I found it myself. It seems there's a known problem with SQL Server 2000 (pre-SP1), where a subquery with computed or aggregate columns causes this error.