Application: kontact (4.9.2)
KDE Platform Version: 4.9.2
Qt Version: 4.8.2
Operating System: Linux 3.2.28 x86_64
Distribution: Ubuntu 12.04.1 LTS

-- Information about the crash:
- What I was doing when the application crashed:

Closed Kontact.  The main window was already closed.  To get rid of a nasty error message, I usually close Kontact or Akonadi that keep runnung in the systray with right mouse -> close.  Then Kontact or Akonadi crashes _sometimes_.
Hope the backtrace can help you.
Good night, =|o)

The crash can be reproduced some of the time.

-- Backtrace:
Application: Kontact (kontact), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fbd986497c0 (LWP 20981))]

Thread 3 (Thread 0x7fbd7b918700 (LWP 20982)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fbd94e38dec in WTF::TCMalloc_PageHeap::scavengerThread (this=0x7fbd95801de0) at wtf/FastMalloc.cpp:2495
#2  0x00007fbd94e38f19 in WTF::TCMalloc_PageHeap::runScavengerThread (context=<optimized out>) at wtf/FastMalloc.cpp:1618
#3  0x00007fbd902ede9a in start_thread (arg=0x7fbd7b918700) at pthread_create.c:308
#4  0x00007fbd95b6ddbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#5  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x7fbd2cdbc700 (LWP 21009)):
#0  0x00007fbd95b62403 in __GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007fbd8fe21036 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fbd8fe21164 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fbd962e3906 in QEventDispatcherGlib::processEvents (this=0x7fbd200008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#4  0x00007fbd962b2e42 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007fbd962b3097 in QEventLoop::exec (this=0x7fbd2cdbbd90, flags=...) at kernel/qeventloop.cpp:204
#6  0x00007fbd961b2057 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#7  0x00007fbd96292b4f in QInotifyFileSystemWatcherEngine::run (this=0x2bc0640) at io/qfilesystemwatcher_inotify.cpp:248
#8  0x00007fbd961b507b in QThreadPrivate::start (arg=0x2bc0640) at thread/qthread_unix.cpp:307
#9  0x00007fbd902ede9a in start_thread (arg=0x7fbd2cdbc700) at pthread_create.c:308
#10 0x00007fbd95b6ddbd in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#11 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fbd986497c0 (LWP 20981)):
[KCrash Handler]
#6  0x00007fbd8e3cd112 in lockInline (this=0x2b67aa8) at /usr/include/qt4/QtCore/qmutex.h:187
#7  QMutexLocker (m=0x2b67aa8, this=<synthetic pointer>) at /usr/include/qt4/QtCore/qmutex.h:109
#8  Nepomuk::Resource::~Resource (this=0x7fbd14004750, __in_chrg=<optimized out>) at ../../nepomuk/core/resource.cpp:142
#9  0x00007fbd8e3cd399 in Nepomuk::Resource::~Resource (this=0x7fbd14004750, __in_chrg=<optimized out>) at ../../nepomuk/core/resource.cpp:147
#10 0x00007fbd962c4d89 in QMetaCallEvent::~QMetaCallEvent (this=0x7fbd1401f2a0, __in_chrg=<optimized out>) at kernel/qobject.cpp:509
#11 0x00007fbd962c4de9 in QMetaCallEvent::~QMetaCallEvent (this=0x7fbd1401f2a0, __in_chrg=<optimized out>) at kernel/qobject.cpp:518
#12 0x00007fbd962b887f in QCoreApplication::removePostedEvents (receiver=0x2d5acb0, eventType=0) at kernel/qcoreapplication.cpp:1669
#13 0x00007fbd962ca9ab in QObjectPrivate::~QObjectPrivate (this=0x2d5db70, __in_chrg=<optimized out>) at kernel/qobject.cpp:171
#14 0x00007fbd962caa29 in QObjectPrivate::~QObjectPrivate (this=0x2d5db70, __in_chrg=<optimized out>) at kernel/qobject.cpp:186
#15 0x00007fbd962cd0b0 in cleanup (pointer=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:62
#16 ~QScopedPointer (this=0x2d5acb8, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qscopedpointer.h:100
#17 QObject::~QObject (this=0x2d5acb0, __in_chrg=<optimized out>) at kernel/qobject.cpp:817
#18 0x00007fbd8e3d3729 in Nepomuk::ResourceWatcher::~ResourceWatcher (this=0x2d5acb0, __in_chrg=<optimized out>) at ../../nepomuk/core/resourcewatcher.cpp:81
#19 0x00007fbd962c6e15 in QObjectPrivate::deleteChildren (this=0x2b68460) at kernel/qobject.cpp:1908
#20 0x00007fbd962cd07c in QObject::~QObject (this=0x2aa5310, __in_chrg=<optimized out>) at kernel/qobject.cpp:927
#21 0x00007fbd8e3c1e09 in Nepomuk::ResourceManager::~ResourceManager (this=0x2aa5310, __in_chrg=<optimized out>) at ../../nepomuk/core/resourcemanager.cpp:289
#22 0x00007fbd962c6e15 in QObjectPrivate::deleteChildren (this=0x258dca0) at kernel/qobject.cpp:1908
#23 0x00007fbd962cd07c in QObject::~QObject (this=0x7fffb7528b60, __in_chrg=<optimized out>) at kernel/qobject.cpp:927
#24 0x00007fbd96cb82be in QApplication::~QApplication (this=0x7fffb7528b60, __in_chrg=<optimized out>) at kernel/qapplication.cpp:1100
#25 0x000000000040363f in main (argc=1, argv=0x7fffb7529188) at ../../../kontact/src/main.cpp:222

Reported using DrKonqi