This error is a R4 to R5 migration error.

The error does not occur in R5.05

This error was introduced in R5.06a apparently and is to do with Stored forms.

lIf the stored form is ticked on the form and the database option "Allow use of Stored forms in this database" is unticked, then you will receive an error message.

Solution: untick "store form in document" in the form properties or

tick "Allow use of stored forms in this database" in database properties