The tech who arrived cleaned some really bad malware which kept loading every time I rebooted. I can say with relief it is now 100% gone thanks to this guy. He also figured out how to remove some persistent popup errors which kept occurring, and he did a great tune-up on it afterwards. It is now running like a champ. After trying others who struggled and couldn't get the job done, I appreciate finally getting someone competent who knew what he was doing! Thank you.