Sorry, I was wrong about the Exit For, it is useful. Also, think you need a Boolean and the Else actually is not needed.
Code:
Dim booContinue As Boolean
booContinue = True
For Each ctl In Me.Controls
If ctl.ControlType = acTextBox Then
If ctl.Tag = "*" And Trim(ctl & "") = "" Then
msg = "Data Required for '" & ctl.Name & "' field!" & nl & _
"You can't save this record until this data is provided!" & nl & _
"Enter the data and try again . . . "
Style = vbCritical + vbOKOnly
Title = "Required Data..."
MsgBox msg, Style, Title
ctl.SetFocus
booContinue = False
Exit For
End If
End If
Next
If booContinue Then DoCmd.BrowseTo acBrowseToForm, "LogIn"
End Sub