I spent some time off and on over the past few days trying to figure out why the Index on my Win7 PC was getting reset and having to totally rebuild. Long story short, it turned out to be the MS Search option in CCleaner. I unchecked the option box and that resolved the issue. Fine, no problem with that.
It took me longer than it should have to figure out what was happening because my brain was zeroed in on the word index(ing) since that's the way Win7 labels it. I passed over the term "MS Search" several times without it dawning on me.
My suggestion is to expand the description from MS Search to something like MS Search & Indexing to make it more intuitive for people with brains wired like mine.