I have this problem, but I run UT in portable mode. The automatic updates and update to beta options are both checked, but greyed out.
Yet, updates are still downloaded into the updates subfolder. uT will randomly decide it doesn't want to run, and instead wants to install. This will be because there is a new version and it wants to install it. The only fix is to manually replace utorrent.exe with the new version in \updates. Then it runs in portable mode again. This forces me to update when I don't want to.
The other night, I had uTorrent shut down while I was reading about the new security flaws. I made sure that utorrent.exe was no longer running. A few hours later, I got a random UAC popup for uT. What would cause the portable version of uT to launch in the middle of a Windows session?