Guide to fixing Launcher error:  The CAS System was unable to initialize: ClientHandler: initialization error: failed to create storage component. After downloading the client uTorrent makes the folder and files readonly (to protect the integrity of the torrent contents...).
As a result when you start the client you get the infamous CAS System error:
Further keywords to aid finding this guide:
failed fetching the CDN configuration file
tact::ClientHandler::Create failed: E_NOT_AVAILABLE To FIX this remove the readonly flag from the folder and it's contents:
Rightclick the folder, find the checkbox for the read-only flag, untick (make it empty), then press Ok / Apply.