>Thanks for the reply. The app has been running a long time. The field is linked to the control. The problem appeared infrequently until new users have been entering a letter in the date field by accident. The system then crashes, instead of giving an invalid date error. I don't know how to prevent this error from occurring. I hope someone has what is probably an obvious solution.
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>Regards,
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>Bill

Do you override grid recordsource at some point?