I had the same problem.
Open up a run dialog by holding down the Windows Key and pressing R. In the "Open" field, enter "services.msc". Look for "Windows Search" and "Superfetch."Go to each of these entries. Right click on one and select "Properties." In the dropdown box labeled "Startup type," choose Disabled. After leaving the properties window, press "Stop" in the upper left corner. Do this for both.
Got this from here http://www.tomshardware.com/forum/id-2813275/disk-usage-100.html