Starting with Windows 2000, Microsoft provided a mechanism to define which utilities are used for backup, disk error checking, disk cleanup, and disk defragmentation.

The default utilities are defined by the following registry entries, even though some are not present and are invoked by default:

Key Name:          SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\BackupPath
  Name:            <no name>
  Type:            REG_EXPAND_SZ
  Data:            %SystemRoot%\system32\ntbackup.exe
 
 
Key Name:          SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\ChkDskPath
  Name:            <no name>
  Type:            REG_EXPAND_SZ
  Data:            %systemroot%\System32\CHKDSK.EXE
 
 
Key Name:          SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\cleanuppath
  Name:            <no name>
  Type:            REG_EXPAND_SZ
  Data:            %SystemRoot%\system32\cleanmgr.exe /D %c
 
 
Key Name:          SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\DefragPath
  Name:            <no name>
  Type:            REG_EXPAND_SZ
  Data:            %systemroot%\system32\dfrg.msc %c:</no></no></no></no>
The easiest way to define these defaults, but preserve your existing entries, is:

1. Run regedit /a oldutil.reg "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer" to export your existing settings.

2. Copy / Paste the following to a Util.reg file:

REGEDIT4

\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\]

\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\BackupPath\]
@=hex(2):25,53,79,73,74,65,6d,52,6f,6f,74,25,5c,73,79,73,74,65,6d,33,32,5c,6e,  74,62,61,63,6b,75,70,2e,65,78,65,00

\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\ChkDskPath\]
@=hex(2):25,73,79,73,74,65,6d,72,6f,6f,74,25,5c,53,79,73,74,65,6d,33,32,5c,43,  48,4b,44,53,4b,2e,45,58,45,00

\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\cleanuppath\]
@=hex(2):25,53,79,73,74,65,6d,52,6f,6f,74,25,5c,73,79,73,74,65,6d,33,32,5c,63,  6c,65,61,6e,6d,67,72,2e,65,78,65,20,2f,44,20,25,63,00

\[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\MyComputer\DefragPath\]
@=hex(2):25,73,79,73,74,65,6d,72,6f,6f,74,25,5c,73,79,73,74,65,6d,33,32,5c,64,  66,72,67,2e,6d,73,63,20,25,63,3a,00
3. Merge the Util.reg file with your registry or run regedit /s Util.reg.

4. Run regedit /s oldutil.reg.to import your previous settings.

5. You can now easily use the Registry Editor to change any of these utilities.