Have you thought about doing a clean sweep and starting again? Clear out all the rubbish.
If you're thinking of doing something as drastic as you are, this may be the best option (assuming you have a 98 disk).
AMD Radeon Adrenalin release date, new features, compatible graphics cards
Inside the iMac Pro - Apple's most powerful Mac yet
iMac Pro release date, UK price & specs
Comment nettoyer Windows et optimiser son PC gratuitement ?