Great call - I should have read the error more carefully. Thanks! I'm glad the next release of DevForce will handle this automatically.
The query is something along the lines of this:
var titles = EntityManager.Titles.Where(x => x.TitleNumber = 1000).Select(x => x.Title1).ToList();
var orders = from order in EntityManager.Orders
join title in titles on order.Title equals title
where order.Status != "Deleted"
select order;
This query is a dumbed-down example, but it includes the join on the List<string>. I could have joined on the Titles table directly in the main query but the generated SQL was atrocious and timing out for us. Splitting things up like this has sped things up quite a bit.