Application: kontact (4.10.5)
KDE Platform Version: 4.10.5
Qt Version: 4.8.4
Operating System: Linux 3.8.0-30-generic x86_64
Distribution: Ubuntu 13.04

-- Information about the crash:
Kontact crash upon launch with no apparent reason
- What I was doing when the application crashed:
start Kontact, 
- Unusual behavior I noticed:
heavy disk&cpu  load by other program

-- Backtrace:
Application: Kontact (kontact), signal: Aborted
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f6e3d5427c0 (LWP 3301))]

Thread 5 (Thread 0x7f6e1ebcc700 (LWP 3302)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f6e39cc7585 in WTF::TCMalloc_PageHeap::scavengerThread() () from /usr/lib/x86_64-linux-gnu/libQtWebKit.so.4
#2  0x00007f6e39cc75d9 in WTF::TCMalloc_PageHeap::runScavengerThread(void*) () from /usr/lib/x86_64-linux-gnu/libQtWebKit.so.4
#3  0x00007f6e3471cf8e in start_thread (arg=0x7f6e1ebcc700) at pthread_create.c:311
#4  0x00007f6e3aabfe1d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 4 (Thread 0x7f6dde2c9700 (LWP 3303)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007f6e39a0da09 in JSC::BlockAllocator::blockFreeingThreadMain() () from /usr/lib/x86_64-linux-gnu/libQtWebKit.so.4
#2  0x00007f6e39cf5cee in WTF::wtfThreadEntryPoint(void*) () from /usr/lib/x86_64-linux-gnu/libQtWebKit.so.4
#3  0x00007f6e3471cf8e in start_thread (arg=0x7f6dde2c9700) at pthread_create.c:311
#4  0x00007f6e3aabfe1d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 3 (Thread 0x7f6dcbfff700 (LWP 3328)):
#0  0x00007f6e3aab33cd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f6e3405a1dc in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f6e3405a304 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f6e3bee5036 in QEventDispatcherGlib::processEvents (this=0x7f6dc40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#4  0x00007f6e3beb538f in QEventLoop::processEvents (this=this@entry=0x7f6dcbffed90, flags=...) at kernel/qeventloop.cpp:149
#5  0x00007f6e3beb5618 in QEventLoop::exec (this=this@entry=0x7f6dcbffed90, flags=...) at kernel/qeventloop.cpp:204
#6  0x00007f6e3bdb7410 in QThread::exec (this=this@entry=0x1dbfb40) at thread/qthread.cpp:542
#7  0x00007f6e3be96edf in QInotifyFileSystemWatcherEngine::run (this=0x1dbfb40) at io/qfilesystemwatcher_inotify.cpp:256
#8  0x00007f6e3bdb9bec in QThreadPrivate::start (arg=0x1dbfb40) at thread/qthread_unix.cpp:338
#9  0x00007f6e3471cf8e in start_thread (arg=0x7f6dcbfff700) at pthread_create.c:311
#10 0x00007f6e3aabfe1d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 2 (Thread 0x7f6dcaf6f700 (LWP 3336)):
[KCrash Handler]
#6  0x00007f6e3a9fd037 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#7  0x00007f6e3aa00698 in __GI_abort () at abort.c:90
#8  0x00007f6e3aa3a5ab in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7f6e3ab4d860 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/unix/sysv/linux/libc_fatal.c:199
#9  0x00007f6e3aa46a46 in malloc_printerr (ptr=0x17a3f40, str=0x7f6e3ab49852 "invalid fastbin entry (free)", action=3) at malloc.c:4902
#10 _int_free (av=<optimized out>, p=0x17a3f30, have_lock=0) at malloc.c:3758
#11 0x00007f6e3be03488 in QString::free (d=0x17a3f40) at tools/qstring.cpp:1235
#12 0x00007f6e37432c89 in ~QString (this=0x2309910, __in_chrg=<optimized out>) at ../../include/QtCore/../../src/corelib/tools/qstring.h:880
#13 QDBusMessagePrivate::~QDBusMessagePrivate (this=0x23098f0, __in_chrg=<optimized out>) at qdbusmessage.cpp:72
#14 0x00007f6e37432d9f in QDBusMessage::~QDBusMessage (this=0xce5, __in_chrg=<optimized out>) at qdbusmessage.cpp:537
#15 0x00007f6e3742e8ad in ~QDBusCallDeliveryEvent (this=0x25ea1d0, __in_chrg=<optimized out>) at qdbusintegrator_p.h:93
#16 QDBusCallDeliveryEvent::~QDBusCallDeliveryEvent (this=0x25ea1d0, __in_chrg=<optimized out>) at qdbusintegrator_p.h:93
#17 0x00007f6e3beba17a in QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0, data=0x17c71b0) at kernel/qcoreapplication.cpp:1586
#18 0x00007f6e3beba4a3 in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1463
#19 0x00007f6e3bee4e83 in sendPostedEvents () at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:236
#20 postEventSourceDispatch (s=0x7f6dbc0012d0) at kernel/qeventdispatcher_glib.cpp:279
#21 0x00007f6e34059f05 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007f6e3405a248 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007f6e3405a304 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#24 0x00007f6e3bee5036 in QEventDispatcherGlib::processEvents (this=0x7f6dbc0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#25 0x00007f6e3beb538f in QEventLoop::processEvents (this=this@entry=0x7f6dcaf6edc0, flags=...) at kernel/qeventloop.cpp:149
#26 0x00007f6e3beb5618 in QEventLoop::exec (this=this@entry=0x7f6dcaf6edc0, flags=...) at kernel/qeventloop.cpp:204
#27 0x00007f6e3bdb7410 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:542
#28 0x00007f6e3bdb9bec in QThreadPrivate::start (arg=0x18e7d30) at thread/qthread_unix.cpp:338
#29 0x00007f6e3471cf8e in start_thread (arg=0x7f6dcaf6f700) at pthread_create.c:311
#30 0x00007f6e3aabfe1d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 1 (Thread 0x7f6e3d5427c0 (LWP 3301)):
#0  0x00007f6e3aab1b0d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007f6e340986cf in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f6e34059d3c in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f6e3405a175 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f6e3405a304 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f6e3bee5036 in QEventDispatcherGlib::processEvents (this=0x163eb60, flags=...) at kernel/qeventdispatcher_glib.cpp:426
#6  0x00007f6e3b3021ae in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#7  0x00007f6e3beb538f in QEventLoop::processEvents (this=this@entry=0x7fffe40dc130, flags=...) at kernel/qeventloop.cpp:149
#8  0x00007f6e3beb5618 in QEventLoop::exec (this=this@entry=0x7fffe40dc130, flags=...) at kernel/qeventloop.cpp:204
#9  0x00007f6e3bebacf6 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1218
#10 0x00000000004033a9 in ?? ()
#11 0x00007f6e3a9e7ea5 in __libc_start_main (main=0x402bb0, argc=1, ubp_av=0x7fffe40dc408, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffe40dc3f8) at libc-start.c:260
#12 0x00000000004038e1 in _start ()

Reported using DrKonqi