>>Are you using a grid for entering your data?
>
>Yes, Naomi
>
>I have done a LOCATE, followed by a GATHER, and then lostfocus of a textbox goes on to calculate and REPLACE a value on the gathered record. I have for the moment wrapped the REPLACE line in a TRY-CATCH.

I remember that this error is usually connected with a grid. There were messages on this problem (bug?) and answers by Alexey T. I think the error may occur if you move the record pointer.

I'll find you several older threads on this topic tomorrow.