After a clean install of Windows Me on a newly formatted hard drive, the 'System Configuration Editor' (SysEdit.exe) is missing. SysEdit edits the DOS mode startup files found in the boot drive root directory. To get it back you need to have a Windows 98 Setup disk. Put the CD into your CD-Rom drive, open a DOS prompt and type in:
Extract D:\Win98\Win98_41.cab SysEdit..exe C:\System
Type 'Exit' then press 'Enter' to exit DOS.