Before you run CCleaner...

And especially CCleaner Pro, before you allow the program to make ANY changes to your Windows computer, CREATE A RESTORE POINT. Don't be trusting of CCleaner Pro, making my mistake that after three months is still not resolved. Driver updater has made the most common use of my PC is as a BSOD launcher. Sometimes on booting, sometimes in the middle of something, and pretty much any time I leave the computer on overnight.

BTW, the seemingly random organization of the official documentation for CCleaner is a really bad joke. I've used the CCleaner free version off and on for years. Last August 2023, I thought it's time to start paying my way while also seeing the advantages of CCleaner Pro. And now I have to beg Piriform to cancel auto renew. Can't do it myself.