I spent a week trying to get MSE re-installed after CCleaner messed me up... I had to go into the registry and delete a key. Then I was able to re-install MSE. Ran CCleaner again this past weekend and poof, my MSE was gone again. Got it back a lot quicker. I came across something in my searches telling me to un-click one of the checkmarks in CCleaner, but I'll have to search that later. Google shows a lot of people have had issues with the 2 together.