I suggest you don't bother to clean it up thoroughly. After backup, format all files and reinstall the system. There is 50g on disk C, so contact the software to install disk D, so disk D is 60- 100g, and disk E plays other files such as audio, video and entertainment, and distributes them by itself. Daily cleaning and maintenance will reduce future troubles. If you use 360, you can clean the system twice a week. System vulnerabilities need to be installed on demand, not all. Cleaning can also be done by an optimization master. I hope it works.