It depends on what happend to you scx/sct file. In many cases you need just to fix a header in the scx table. Sometimes (in the first version of Windows 2000 or because of viruses) the scx/sct file became comletly useless. In this case you can use only old or backup version of sct/scx. You may find my yrecover.exe in the download section here to recover sct/scx from the valid exe/app file.