I am unable to download CCleaner.
it would not update and when I removed and attempted to reinstall ; I am unable to do so.
Defraggler will also no longer update.
You can also download Piriform products at:
Sounds like one of your Security programs is stopping install. please list the following
Windows Version and Service Pack Level
All Security Products running on your machine (Firewall, Antivirus, AntiMalware)
Be sure that you are only downloading from the site andavari linked or the downloads page on this site.
Be sure that you are running as an administrator on the machine and that (if running vista or windows 7) you are running the installer with elevated privilages (UAC prompt click yes)