Startup with iPhone plugged in causes inability to logout

In 14.04 startup with an iPhone 3G plugged in causes several problems. Changes to Unity made with Unity Tweak Tool are not recognized after such a startup, and attempting to logout hangs after the desktop icons are erased and only the desktop background remains. Startup without the iPhone plugged into a usb port works fine, as does operation when plugging in the iPhone after startup.

The iPhone is jail-broken and is set to tether. Synaptic shows only libplist1, libimobiledevice, usbmuxd and libusbmuxd2 installed related to iPhones.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: libimobiledevice4 1.1.5+git20140313.bafe6a9e-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-8.28-generic 3.13.2
Uname: Linux 3.13.0-8-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CurrentDesktop: Unity
Date: Wed Jul 30 06:10:49 2014
InstallationDate: Installed on 2014-01-11 (199 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Alpha amd64 (20140109)
ProcEnviron:
 LANGUAGE=en_IN:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_IN
 SHELL=/bin/bash
SourcePackage: libimobiledevice
UpgradeStatus: No upgrade log present (probably fresh install)