Hi nonturbo,
Firstly I would suggest a repair and compact.
Secondly I would examine the tables/queries that the form is running on. If you are running a form based on a query or table, try adding data directly to the table or query to see if the same message arises - this might isolate the problem to table relationships or queries.
Thirdly, (NB - save a back up of your form before doing this) if the message only arises in the form, I would suggest removing the link in the form to its underlying recordset, closing and saving the form, and then reopening without a recordset to see if this gives the message. Then put the recordset back, close and save and reopen again. Another area to check is the code (if any) on the OnOpen, On Load or OnCurrent properties of the form - try remming out the code and reopening.
Hopefully this will help to isolate the source of the message.
Finally, I have noticed in Access97 (& 2000) that if you have an unusual error, breaking something, saving it, and then rebuilding just the same can sometimes sort out the problem. Hope this helps, jobo123