>Why can't I make a query ivolving four tables

Because the Query Designer has issues. You can create the query (or view) in code to get it to work properly, but instead of:

SELECT * ;
   FROM tableA ;
      JOIN tableB ;
         JOIN tableC ;
            ON tableB.id2 = tableC.id2 ;
         ON tableA.id = tableB.id

create it like:

SELECT * ;
   FROM tableA ;
      JOIN tableB ON tableA.id = tableB.id ;
      JOIN tableC ON tableB.id2 = tableC.id2

In other words, list the joins sequentially, instead of nested, as the QD does.

This has been fixed in VFP8, but in the meantime, writing the code manually is your best bet.