I want to lock down some of the records on the form where the flag column for
that record is marked "yes".

for example I want to nobody can change the "Purchase Order table/query" via
"Purchase Order form" if one control/column named "Status" of the "Purchase
Order" form/table has been marked as "Finished".
They can view the Purchase Order form and navigate the records but can not
update the Purchase Order information as soon as the "Status" is "Finished".

I think I can not using "On Open" event procedure of the form because
"OnOpen" only trigged when the form is opened, but I need navigate the record
and if the status is "Finished" on that purchase order record then lock down
all the controls on the form by using "setvalue" for the enable property, am
I right?

So on the form which event I should use? any solution for that? I would
appreciate your answer or comments!