Since 10.0RTM, when browsing pre-defined spatial references (ie. trying to select a proper data frame coordinate system), people often select different spatial references and click "modify" to view the details. But when you do so, the dialog box always shows the details for the first one you choose, not updating itself with new info. You have to close the how "select coordinate system" window to get the details for another one. That's annoying. Hope there would be a fix in SP5.