If you are on Windows XP or Vista, you can safely use CCleaner version 5.64, please download our slim build here. This version will only ever receive critical security updates.
Like Microsoft, we recommend retiring your Windows XP/Vista computer and upgrading to a new one. This is especially true if your computer is connected to the internet, because XP and Vista are no longer receiving security updates and are vulnerable to online threats.
Microsoft has the following information for users of Windows XP: