Hi,
For what it's worth I just had a similar problem. It occured when I did an SQL - Insert to add a new record to an (opened exclusive) rewriteable cursor in a grid.

It then went immediately to a modal form for the user to fill in the rest of the new record's values. When the form's combo box was clilcked a "Record is in use by another" message immediately came up. I would also get the same error message later on whenever I attempted to add new records to this rewriteable cursor (still opened exclusive).

In my case the problem went away when I did a LOCATE for the newly inserted record's primary key immediately after the SQL - Insert. (Go figure!)

I really have no idea what was occuring but the LOCATE worked around the problem. I'd appreciate to hear what you might discover. Thanks!