First start by reading the official documentation for solutions to install problems.
Other possible solutions when CCleaner won't install:
- Make sure the installer isn't named CCleaner.exe, if it is rename it to something else like: ccsetup400.exe
- Exit running programs that may interfere, or temporarily disable them, i.e.; antivirus software, etc.
- Make sure CCleaner isn't already running. To find out if it is open Task Manager to see if CCleaner.exe is in the list of running processes.
- Reboot your computer.
- Try to install CCleaner in Safe Mode. Credits go to Hazelnut for this tip.
- If the above attempts fail download the Portable version of CCleaner, then unzip it to use CCleaner, you can even unzip it into the folder where an older version of CCleaner is installed to update it. Note: If you're updating an already installed version of CCleaner using this method delete the portable.dat file before launching the new version of CCleaner.
- If downloading CCleaner fails which some people have reported try a different web browser (if you don't want to install a different web browser you could instead use a portable edition of popular web browsers). If the download is corrupted you may even need to clear out your web browser cache ("Temporary Internet Files").
- If after trying everything listed above you're still having issues scan your computer with trusted anti-virus and anti-malware software.
To avoid rip-off versions (which could be malware in disguise) only download CCleaner from the official download sites Piriform CCleaner, or from FileHippo.com.
Edited by Andavari, 09 April 2013 - 06:08 PM.
Updated topic information