Here it is:
Go to Start => Run and type in "regedit" {without the quotes}
Navigate to:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows Defender\Scan
Right-click this key, and click on 'Permissions'
Select your username (highlighted), click 'Full Control' in the 'Allow'
column, and click 'Apply'
With the the above key highlighted,
Go to Edit => New => DWORD value, and type in "DisableRestorePoint"
{without the quotes} in the box, and hit Enter.
Double-click on DisableRestorePoint in the right-hand pane, and set the
Value to 1 (hexadecimal)
Now, undo the Permissions you set earlier:
Right-click the 'Scan' key in the left-hand pane, and choose
'Permissions'
With your username selected (highlighted), uncheck 'Full Control' in
the 'Allow' column, and click 'Apply'
Close the registry editor.
