Just leave it running overnight. The length of time depends on a few things, such as size of the disc, How badly it's fragmented and what problems there are. Give it another whirl. As an afterthought do it in Safe Mode. That will ensure that there are only the minimum fo drivers loaded. If you don't know how to boot into safe mode try holding the cntrl key down immedeately after switching on. There are other keys to try instead but this will depend on your motherboard.