I've experienced this problem a few times with uTorrent - when attempting to open the application, or opening a new torrent file, the following error message is displayed;
"A newer version of uTorrent is already running. Please shut down uTorrent and try again"
After shutting down uTorrent and opening it again, the same message is displayed.
The issue appears to be related to uTorrent getting confused about which version it has installed, and wants to run.
Make sure uTorrent has been closed (you may need to kill the task from Task Manager)
Go to the uTorrent installation directory (usually %appdata%\uTorrent or C:\users\%username%\appdata\roaming\uTorrent) and delete the Updates folder (and everything within it). If you get an error advising the files are locked/cannot be opened, you will either need to kill the stuck uTorrent process from Task Manager, or simply restart your computer.
Try starting uTorrent again after removing the Updates folder - it should now open correctly