OK...this is the AfterUpdate code you created:
Private Sub cmbSSN_AfterUpdate()
If IsNull(Me.cmbSSN) Then
Me.Filter = ""
Exit Sub
End If
If DCount("CustomerID", "Customers", "[SSN] = [Forms]![frmCustomersPOP]![cmbSSN]") < 1 Then
MsgBox "No entry for this SSN number - please complete a new record"
DoCmd.GoToRecord acActiveDataObject, , acNewRec
Me.SSN = Me.cmbSSN
Else
DoCmd.ApplyFilter , "[SSN] = Forms!frmCustomersPOP!cmbSSN"
End If
End Sub
However, I got it to work once the first time I went in, and then I experimented with it, making mistakes the user would (and will when we get on the floor), like putting in the wrong number and trying again. After that, when I put in a new number, it flickered past, updating the record, then the thing went straight to a new, empty record (I can tell b/c the field you added had AutoNum in it). If I hit "back", I could get to the new SSN. What might cause this that it does not work the same way every time? Why is it creating a new record AFTER holding the SSN?