Linux Mint 13 KDE. 
Downloading a large number of level 3 packages as recommended by Update Manager. System froze up entirely after downloading a certain percent, unrecoverable. 

Note that this has happened to me before on Linux Mint Cinnamon.

Reproducible: Sometimes

Steps to Reproduce:
1.Set Update Manager to download all recommended updates on a fresh install. 
2. Click OK on added files needed for packages
3. watch system freeze up after downloading a certain percentage of all files.
Actual Results:  
Progress bar of downloads comes to a stop at a certain percentage and system freezes up entirely requiring hard boot. 

Expected Results:  
Downloaded and installed all updates.

Not sure if this helps:
-- Backtrace:
Application: KDE Dæmon (kdeinit4), signal: Segmentation fault
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0xb77cf740 (LWP 1312))]

Thread 3 (Thread 0xb3239b40 (LWP 1375)):
#0  0x00ea3416 in __kernel_vsyscall ()
#1  0x0089d800 in poll () from /lib/i386-linux-gnu/libc.so.6
#2  0x011d5a3b in g_poll () from /lib/i386-linux-gnu/libglib-2.0.so.0
#3  0x011c806e in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#4  0x011c852b in g_main_loop_run () from /lib/i386-linux-gnu/libglib-2.0.so.0
#5  0x03daa0ea in ?? () from /usr/lib/i386-linux-gnu/libgio-2.0.so.0
#6  0x011eb673 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#7  0x02583a11 in ?? () from /usr/lib/nvidia-current/libGL.so.1
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

Thread 2 (Thread 0xb28ffb40 (LWP 1456)):
#0  0x00e67c64 in __pthread_mutex_unlock_usercnt () from /lib/i386-linux-gnu/libpthread.so.0
#1  0x008b9ab4 in pthread_mutex_unlock () from /lib/i386-linux-gnu/libc.so.6
#2  0x012073d0 in g_mutex_unlock () from /lib/i386-linux-gnu/libglib-2.0.so.0
#3  0x011c7755 in g_main_context_prepare () from /lib/i386-linux-gnu/libglib-2.0.so.0
#4  0x011c7f6f in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#5  0x011c81c1 in g_main_context_iteration () from /lib/i386-linux-gnu/libglib-2.0.so.0
#6  0x010538e7 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#7  0x0101f50d in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#8  0x0101f7a9 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#9  0x00f0894c in QThread::exec() () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0x00ffcb5d in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#11 0x00f0bde0 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#12 0x02583a11 in ?? () from /usr/lib/nvidia-current/libGL.so.1
Backtrace stopped: previous frame inner to this frame (corrupt stack?)

Thread 1 (Thread 0xb77cf740 (LWP 1312)):
[KCrash Handler]
#7  0x02e9b344 in SecretStorage::walletOpenedForRead(bool) () from /usr/lib/libknmservice.so.4
#8  0x02e96692 in ?? () from /usr/lib/libknmservice.so.4
#9  0x010376b1 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0x00ccb4ed in KWallet::Wallet::walletOpened(bool) () from /usr/lib/libkdeui.so.5
#11 0x00ccb5dd in KWallet::Wallet::walletAsyncOpened(int, int) () from /usr/lib/libkdeui.so.5
#12 0x00ccb732 in ?? () from /usr/lib/libkdeui.so.5
#13 0x010376b1 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#14 0x00d02e7d in ?? () from /usr/lib/libkdeui.so.5
#15 0x00d056c1 in ?? () from /usr/lib/libkdeui.so.5
#16 0x00d059dc in ?? () from /usr/lib/libkdeui.so.5
#17 0x00dfda38 in ?? () from /usr/lib/i386-linux-gnu/libQtDBus.so.4
#18 0x00e07c8d in ?? () from /usr/lib/i386-linux-gnu/libQtDBus.so.4
#19 0x0103bc7b in QObject::event(QEvent*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#20 0x07294ed4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#21 0x0729a30d in QApplication::notify(QObject*, QEvent*) () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#22 0x00b87b61 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdeui.so.5
#23 0x0102097e in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#24 0x01024ad8 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#25 0x01024e0c in QCoreApplication::sendPostedEvents(QObject*, int) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#26 0x01053494 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#27 0x011c7cda in g_main_context_dispatch () from /lib/i386-linux-gnu/libglib-2.0.so.0
#28 0x011c80e5 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#29 0x011c81c1 in g_main_context_iteration () from /lib/i386-linux-gnu/libglib-2.0.so.0
#30 0x01053887 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#31 0x0734daaa in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#32 0x0101f50d in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#33 0x0101f7a9 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#34 0x01024eba in QCoreApplication::exec() () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#35 0x07292a74 in QApplication::exec() () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#36 0x0677b959 in kdemain () from /usr/lib/kde4/libkdeinit/libkdeinit4_kded4.so
#37 0x0804f8a4 in _start ()