I now get this problem too, but it only started recently. The first time I saw it was immediately after I had downloaded a new version of CCleaner, when it ate my antivirus protection (the rest of PCGuard still seemed to work.) Rebooting took ages and came up with a couple of Windows Installer messages "Preparing to install..." (I got the impression that PCGuard was trying to find something that had vanished.) I reactivated the antivirus via the Support page, and all was OK until the next time I downloaded another CCleaner update. Same problem - but this time I had to uninstall and reinstall PCGuard.
Is there a cookie or a dat or ini file that CCleaner removes but which is essential to PCGuard? If so, could someone please tell me what it is? Then I won't clean it away.
