I’ve used Avast on and off for quite some time. at this moment, I got this one free from an in store promotional offer. I usually just run windows defender and I’ve been pretty secure since installing Windows10. I probably will remove avast from my system for the new year. It gets a little frustrating with the ongoing accessibility issues. However, it has worked well for me as an antivirus software and only that. My registry cleaner for a number of years has been CCleaner. It has worked well for me and is currently working great for me. And CCleaner is very accessible which is a plus for me. but ultimately; a messed up registry is usually fixed by other tools associated with CCleaner. Your computer usually goes down with a Windows OS issue or a malfunctioning app. Scanning your OS with the sfc /scannow command in an elevated command prompt and uninstalling the troubled app and reinstalling it usually resolves most of your issues.