I don't think this is a known issue because i have vista and CCleaner cleans all the browser's histories. I had CCleaner version 1.39 though, may be it help if you close all your browsers before cleaning it -) . If that still not help then maybe you should go to filehippo.com and download ccleaner1.39 -which i don't think is the problem cause v1.40 suppose to be better then 1.39, something must of block CCleaner from ccleaning your browser's history.