So many answers to some of this post, but, I'll start with, turn on your spell checker! :) My spelling sucks sometimes, so mine is always on. lol.
Hitman Pro seems to work when normal AV types don't, or can't find the bug. Seen lots of MS techs use it. I don't, but I don't seem to get those nasty bugs. Thank God. You must log on some "interesting sites" to get the nasty ones. Grin.
CCleaner is a VERY MILD reg cleaner, don't think it could do much hard to anyone's puter. Does no deep cleaning what-so-ever!!
My other two, do but that's why I got em. Ace Utilities has been my long time favorite, but lots of people never heard of it,Glary's ain't bad, for free ware app. lots of features and all fer free too. I also have edited my registry manually too, but not much lately.
Of course always have a backup, just incase. I have complete image backups, and registry backups. Makes life with Windows a little easier. Plus I play around with all kinds of stuff, tweaking this and that. OR deleting this or that. :) Heck I think a lot of us do in here. I've been playing on computers for over 30 years now, seen all kinds of mistakes done by ME over those years, but it all part of playing on my puter, and I enjoy doing so. We all do things a little different, makes life interesting I think.