I had the same on feb 9. Downloaded the latest CCleaner and after running it could not open Thunderbird nor Firefox anymore. Received a message 'thunderbird active but cannot open' or something to that effect. Also the folders in 'my documents' had disappeared. Thank god I had just installed a back up drive and had made a backup with File History. After a restart 'control panel' became visible when searchin in W10 but it did not open. Could not find it anymore. I restored the my documents files and managed to get Chrome operational with some difficulties. The bad thing is all this happened on the laptop of an older lady who asked for my help. This issue seems to have happened als in 2017, i.e. CCleaner destroying Mozilla. Not sure how to proceed, I hope the original emails are still on the laptop. She can mail with an iPad. Great shame on Piriform to let this happen twice!!!