I had the free version years ago and it never caused issues, only recently Pro started messing up Office 2016
I've confirmed that CCleaner PRO does corrupt OFFICE 2016 and thus I had to do a reinstall of OFFICE 2016. I've run CCLEANER pro and then clicked on OFFICE 2016 products and sure enough, files were corrupted. Did reinstall of OFFICE 2016,,,,,,,,,ensured the office products were all shut down, ran ccleaner pro again, and once again files were corrupted. Not using CCleaner PRO until i'm told there's a fix for this issue.