Very odd experience: I rebooted to Safe Mode- downloaded CCleaner from site (it was previous version 5.68.0.7120)- I downloaded again and got 5.69.0.7865, tried to run as Admin. and no Admin., got error 'Installer integrity check has failed.'- downloaded again & got 5.69.0.7865, run as Admin. and it installed! Been in computer business for 40+ years and never encountered one as bizarre as this one. CCleaner tech support should definitely investigate. Thanks to everyone for help.