If you are using the free version of CCleaner, you have to manually kill the process 'dllhost.exe' prior to cleaning. I find the easiest way to do it is through Process Explorer. You could also make a .bat file similar to this: @echo off taskkill /f /im dllhost.exe start "" "C:\Program Files\CCleaner\CCleaner64.exe" /AUTO If you have CCleaner PRO, choose 'Options' then 'Monitoring'. Uncheck the box 'Enable Browser Monitoring'. Hope this helps.