>>Look at the tables that the cursor gets its data from for an index key expression problem.
>
>Is this a clue?
>
>The problem only occurs ONCE per session.
>
>In other words once I've ignored all the error messages and it does what I wanted it do in the first place, I can then repeat it in the same form/table combination - or any other form/table combination with no further protest. But if I exit the app then I'll the problem the first time I try it on re-entry.
>
>Does this tell us anything? If so what?

Harry,

It tells us that something is looking for a variable or field that it cannot find. It is NOT in your form because the same things happens when you run the same code in a prg. We know the prg isn't doing anything to refer to the variable or field, so the only other place that the errant reference can be coming from is the data tables themselves. It could be an index key expression, one of the events or properties associated with a table or field in the dbc, a currupt index, or some other aspect of the data tables.