During the digitizer, you may find Undo does not function at all when clicking on the "Undo" button. It is simply ignored. If you open the undo list and select a number of undo steps for the undo action, ES e4 gives a System Error.
It is identified that this issue is caused by the old version of CorelDRAW software installed on user's PC. The workaround is to uninstall all of the old versions of CorelDRAW software.