Thanks. At least we know it now.

>Hi Yuri,
>
>Thought you may be interested, my internal consistency error turned out to be a bug in VFP7.0, fixed in 8.0 according to Microsoft (giving an error message rather than crashing).
>It appears that code I had run in the formset.load event had affected the data environment. Unlike with form.load, formset.load is run AFTER the dataenvironment has been loaded.
>
>Blair