>Please see attached - looks like you forgot to order result in DESC order.

When we changed it to WHERE EXISTS, I forgot to add another ORDER BY:

DECLARE @NoMember Integer

SET @NoMember=1

SELECT Thread.Numero,Thread.Title,Thread.Url,Thread.AddDate 
FROM Thread (NOLOCK) 
WHERE EXISTS 
(SELECT 1 FROM (SELECT TOP 10 Reply.NoThread FROM Reply (NOLOCK) WHERE Reply.NoMember=@NoMember ORDER BY 1 DESC) Temp
 WHERE Temp.NoThread=Thread.Numero)
  ORDER BY 1 DESC

It should be ok now. This might require a login however.