If you are using the McAfee Internet Security suite, then certain programs will not work properly by default. This is because McAfee blocks off all ports that it does not recognize or that have not been previously authorized. Ports are the way that traffic enters and exits a router online. If you want to enable McAfee to work with uTorrent, you have to manually grant the program permission from within McAfee.
Click "Start," then "Programs," and then "McAfee Internet Security."
Click "Internet & Network," and then "Configure."
Click "Advanced" and then "Program Permissions."
Scroll down to "uTorrent." Click "Action" and then select "Allow Access."