>(this is a Compact Framework app, but I don't think that should make a difference).
>
>This question comes from my almost complete lack of any .NET WinForm experience in CRUD apps.
>

Turns out this is happening because both a new row and the particular test records I was using had a NULL value in one of the fields being bound to a NumericUpdown control. It apparently didn't like the nulls so it would refuse to navigate to records that had them.