"Does anybody know how to figure out which required field was left blank so that I can position the cursor in it?"

Maybe you could use the Tag property, and when you loop through the controls, if the Tag has a specific entry then you know it's required, then you test if they plugged in anything. Of course, you would have to load in the Tag values, but only once.

I usually do all of my required fields in code, not in the table. In this way, I can require certain fields for certain users. For example, my manufacturing job tickets are started by the receiving clerk, but they don't know all the info, so they're allowed to skip some of the fields. However, when the customer service rep gets the job ticket, they do need to complete all of the fields, and they can't leave that screen until they're done.

I use something like this:

With Me
    If IsNull(.fldOne) Or IsNull(.fldTwo) Or IsNull(.fldThree) Then
        resp = MsgBox("all fields are required",vbOKOnly+vbExclamation)
        If IsNull(.fldOne) Then
            DoCmd.GoToControl "fldOne"
        ElseIf IsNull(.fldTwo) Then
            DoCmd.GoToControl "fldTwo"
            DoCmd.GoToControl "fldThree"
        Exit Sub
End With