hmmm, sounds fishy. XXX should not need to qualify the table name (with the owner name) when selecting from their own table. While logged in as XXX, run the following code to confirm your table is owned by XXX and that the table ownerid is the same as the logged in userid (myUserID should be the same as tableOwnerID)
select user_id() myUserID
,objectproperty(object_id('XXX.A'), 'ownerid') tableOwnerID
Be One with the Optimizer
TG