I have windows 8.1. My task manager shows disc usage at 100%. Tried y ways to correct it with no luck. Finally read a forum post that said to change performance level from balanced to high performance and it worked...not to mention improved performance. If you have the same issue, try it...it worked for me.
It's almost unbelievable what the last post in the thread says that CCleaner rectified it. Its registry cleaner is very good but also very safe what in other words mean that it doesn't go to the registry too deeply. Yet it was enough. Really interesting.
