@TheOwner I began my reply as follows: Using  Win 10 Pro 1803: I tried following your instructions above but would you please clarify "3.Disable CCupdate task in task manager" . In my task manager (Win 10 Pro) I have an associated process called "CCleaner64.exe" and I also have a "CCleaner" entry in the Start-up tab. I've disabled the startup entry, and stopped the process many times (and modified the options in CCleaner itself)  but it recurs after a few minutes as others have stated. Where exactly in task manager did you see CCUpdate task?  Or did you mean Task Scheduler Library which does indeed have a CCleaner Update task in "Ready" status. Problem with disabling that (IMO) is that you then would not get alerted to any updates. However, that may be irrelevent because.......... EDIT: Having had a poke about "under the bonnet" as it were, I stopped the monitoring pro-tem, and then went to C:\Program Files\CCleaner and manually ran CCUpdate.exe. It did NOT restart the monitoring so that has nothing to do with it, neither are there any errant Services. Looking at ccleaner.ini, all references to monitoring are set to  0 Used PC as normal for 4 hours.. Monitoring did not start, even after I ran CCleaner manually.  In ccleaner.ini, all references to monitoring remained set  to 0 Then rebooted Windows and once again Monitoring started, it's again enabled in  the Task Manager Start-up tab and, in CCleaner Options, "Enable Active Monitoring" is ticked and in ccleaner.ini there is now a line saying "Monitoring=1" However, i think it would be possible to stop this problem occurring by modifying the Registry which contains the following entry: [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run]
"CCleaner Monitoring"="\"C:\\Program Files\\CCleaner\\CCleaner64.exe\" /MONITOR" It's presumably this that causes the ini file to be changed at System Boot and removing the "CCleaner Monitoring"entry is the path I shall follow if Piriform don't come up with a more elegant solution. However I intend to wait and see for a few days as I think a solution from the Developer is not only more elegant but will prevent the issue reoccurring with subsequent releases! I for one don't want to have to edit my Registry every time CCleaner is updated especially as I have 5 PCs to manage!! Please Mr/Ms Developer..what about it?