Are you no longer able to get into Windows task manager to stop processes and applications from running? This is a sure sign that you have adware, spyware, malware, and or viruses on your computer. CCleaner exe is free and basically just deletes any unnecessary files and registry items to make your computer run better. I think you may still have a virus or some kind of malware on your computer if Windows Task Manager won't open up, after running CCleaner.
If you haven't already, run a full system scan with another FREE program called MalwareBytes used for deleting malware, and then run a full virus scan with your installed antivirus software. I know they may take a while to run but I have seen running a complete virus scan including CCleaner and Malwarebytes scans, which fixed major adware, spyware, malware, virus issues. If you are still unable to get Windows task manager to work after running scans with the three afore mentioned programs then you might try booting the computer into windows safe mode and this time try using System Restore.
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