Ive seen alot of posts saying using utorrent will cause problems with scrambling, but i guess it all depends on how good your internet connection is.... Its not so much your internet speed, but how many devices are connected to it .... Eventhough you delete the torrent utorrent might be updating in the background...or your AV might be installing updates....or your you could have stuff on your computer youve forgot about thats connected and using bandwith....
My download speeds about 38MB and 9MB up but when my sisters round with the kids all using their devices on my wifi i get a lot of scrambling...So it could be other people in the house , aswell as you, thats causing you problems.....