What's SET TABLEVALIDATE in the application?

>Two clients: one with a commercial systems with thousands of installations, the other is custom.
>One app has about 15 users, the other just 2. Both have been running well for several years. Recently we have been experiencing lost records at both clients. It happens about once every week or two. The loss is a single record, ususally a header record in a header/details structure.
>
>The file is not corrupted. It opens and processes existing records without problems.
>
>I know hardware problems can cause garbage characters to appear in tables, but in this case a complete single record is cleanly gone. I have wondered about possilbe buffering problems with the data in a buffer not being written out for some unknow reason. Any suggestion on how to test this or what ot look for?
>
>All thoughts happily accepted, except ungrading the apps to VP9. That's already on my list.