Gerard,
There is no native grid behavior that would cause this to happen. You need to look through your grid inheritance hierarchy to find the culprit.
>it is quite possible that a Gris refresh is triggered... but how would that have the effect of moving the record to the first one displayed on the grid ?
>
>Is there a propery somewhere that tells it to do this. I would have thouught that it should stay in the same place ???