Circular refrence are generally ceated when there is a loop type structure in data model ie the field are linked to one other in form of loop in the diffrent tables.
In qlikview we should avoid circular refrence,because they effect a lot in the processing and sometimes also the unmatchable data.
we can remove them by using aliasing,mapping,joining etc.
Circular reference is created due to some fields that are creating loop ammong the tables when theu are all ready connected with any key and one of its fields having same name so it got reference to the field and they create a circular reference.
It is good if you avoid it it is not good to remove circular reference try rename the field or try to map or give different name to the tables like use Qualify * ; command like
After this code all table fields name start with table name like Table2.yourfield etc rest of the fields come same order