I am not 100% sure if this crash is related, but as the backtrace looks similar, I'll post it here too... Please tell me if its another bug, then I can give it a report of its own...

What happened:

I selected a folder and it took some time until this folder came up (my IMAP server is having some hickups at the moment and needs ~1 minute to start showing the folder information). 
I *guess* during that time kontact periodically poled for new emails on that same IMAP server. Bottom line: While kontact was running in the background, it crashed with the following backtrace:

Application: Kontact (kontact), signal SIGABRT

Thread 1 (Thread 0xb4da0720 (LWP 21887)):
[KCrash Handler]
#6  0xffffe424 in __kernel_vsyscall ()
#7  0xb5421690 in *__GI_raise (sig=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#8  0xb5422ed8 in *__GI_abort () at abort.c:88
#9  0xb7d3f32f in qt_message_output (msgType=QtFatalMsg, 
    buf=0xbf938ef0 "ASSERT failure in QMutexLocker: \"QMutex pointer is misaligned\", file ../../include/QtCore/../../src/corelib/thread/qmutex.h, line 103") at global/qglobal.cpp:2108
#10 0xb7d3f3ee in qFatal (msg=0xb7e88e2c "ASSERT failure in %s: \"%s\", file %s, line %d") at global/qglobal.cpp:2309
#11 0xb7d3f434 in qt_assert_x (where=0xb7e889db "QMutexLocker", what=0xb7e889be "QMutex pointer is misaligned", file=0xb7e88978 "../../include/QtCore/../../src/corelib/thread/qmutex.h", line=103)
    at global/qglobal.cpp:1886
#12 0xb7e4f5ec in QMetaObject::activate (sender=0x850d760, from_signal_index=5, to_signal_index=5, argv=0xbf93afe8) at ../../include/QtCore/../../src/corelib/thread/qmutex.h:103
#13 0xb7e513d8 in QMetaObject::activate (sender=0x850d760, m=0xb69552e8, local_signal_index=1, argv=0xbf93afe8) at kernel/qobject.cpp:3098
#14 0xb68f097b in KPIM::ProgressItem::progressItemProgress (this=0x850d760, _t1=0x850d760, _t2=9) at /var/tmp/portage/kde-base/libkdepim-4.1.69/work/libkdepim_build/libkdepim/progressmanager.moc:102
#15 0xb68f09ad in KPIM::ProgressItem::setProgress (this=0x850d760, v=9) at /var/tmp/portage/kde-base/libkdepim-4.1.69/work/libkdepim-4.1.69/libkdepim/progressmanager.cpp:108
#16 0xb1ad82b8 in KPIM::ProgressItem::updateProgress (this=0x850d760) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail-4.1.69/libkdepim/progressmanager.h:142
#17 0xb1ba1381 in KMAcctImap::postProcessNewMail (this=0x84be2b0, folder=0x84f7200) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail-4.1.69/kmail/kmacctimap.cpp:400
#18 0xb1ba1f6e in KMAcctImap::qt_metacall (this=0x84be2b0, _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbf93b238) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail_build/kmail/kmacctimap.moc:83
#19 0xb7e4f4e1 in QMetaObject::activate (sender=0x84f8740, from_signal_index=<value optimized out>, to_signal_index=35, argv=0xbf93b238) at kernel/qobject.cpp:3028
#20 0xb7e513d8 in QMetaObject::activate (sender=0x84f8740, m=0xb1eff214, local_signal_index=0, argv=0xbf93b238) at kernel/qobject.cpp:3098
#21 0xb1bb168b in KMFolderImap::folderComplete (this=0x84f8740, _t1=0x84f8740, _t2=true) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail_build/kmail/kmfolderimap.moc:204
#22 0xb1bb1997 in KMFolderImap::finishMailCheck (this=0x84f8740, dbg=0xb1ded5a5 "getMessage", state=KMFolderImap::imapFinished)
    at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail-4.1.69/kmail/kmfolderimap.cpp:2465
#23 0xb1bb4f41 in KMFolderImap::getMessagesResult (this=0x84f8740, job=0x88a0188, lastSet=true) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail-4.1.69/kmail/kmfolderimap.cpp:1741
#24 0xb1bb4fa6 in KMFolderImap::slotGetLastMessagesResult (this=0x84f8740, job=0x88a0188) at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail-4.1.69/kmail/kmfolderimap.cpp:1749
#25 0xb1bbf29a in KMFolderImap::qt_metacall (this=0x84f8740, _c=QMetaObject::InvokeMetaMethod, _id=30, _a=0xbf93b44c)
    at /var/tmp/portage/kde-base/kmail-4.1.69/work/kmail_build/kmail/kmfolderimap.moc:184
#26 0xb7e4f4e1 in QMetaObject::activate (sender=0x88a0188, from_signal_index=<value optimized out>, to_signal_index=7, argv=0xbf93b44c) at kernel/qobject.cpp:3028
#27 0xb7e513d8 in QMetaObject::activate (sender=0x88a0188, m=0xb7cbaee8, local_signal_index=3, argv=0xbf93b44c) at kernel/qobject.cpp:3098
#28 0xb7bb49c5 in KJob::result (this=0x88a0188, _t1=0x88a0188) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kdecore/kjob.moc:186
#29 0xb7bb4e3c in KJob::emitResult (this=0x88a0188) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kdecore/jobs/kjob.cpp:290
#30 0xb767f462 in KIO::SimpleJob::slotFinished (this=0x88a0188) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/job.cpp:489
#31 0xb767f7c0 in KIO::TransferJob::slotFinished (this=0x88a0188) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/job.cpp:958
#32 0xb7685a6e in KIO::TransferJob::qt_metacall (this=0x88a0188, _c=QMetaObject::InvokeMetaMethod, _id=7, _a=0xbf93b6a8)
    at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kio/jobclasses.moc:336
#33 0xb7e4f4e1 in QMetaObject::activate (sender=0x8611660, from_signal_index=<value optimized out>, to_signal_index=8, argv=0x0) at kernel/qobject.cpp:3028
#34 0xb7e513d8 in QMetaObject::activate (sender=0x8611660, m=0xb77dbe84, local_signal_index=4, argv=0x0) at kernel/qobject.cpp:3098
#35 0xb771929b in KIO::SlaveInterface::finished (this=0x8611660) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kio/slaveinterface.moc:163
#36 0xb771adaf in KIO::SlaveInterface::dispatch (this=0x8611660, _cmd=104, rawdata=@0xbf93b844) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/slaveinterface.cpp:175
#37 0xb771b83f in KIO::SlaveInterface::dispatch (this=0x8611660) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/slaveinterface.cpp:91
#38 0xb770eb2f in KIO::Slave::gotInput (this=0x8611660) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/slave.cpp:322
#39 0xb770fe0d in KIO::Slave::qt_metacall (this=0x8611660, _c=QMetaObject::InvokeMetaMethod, _id=2, _a=0xbf93b968) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kio/slave.moc:75
#40 0xb7e4f4e1 in QMetaObject::activate (sender=0x860fbf8, from_signal_index=<value optimized out>, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3028
#41 0xb7e513d8 in QMetaObject::activate (sender=0x860fbf8, m=0xb77d8960, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3098
#42 0xb7654ec1 in KIO::Connection::readyRead (this=0x860fbf8) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kio/connection.moc:84
#43 0xb7655b53 in KIO::ConnectionPrivate::dequeue (this=0x8611718) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kio/kio/connection.cpp:82
#44 0xb76568e0 in KIO::Connection::qt_metacall (this=0x860fbf8, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0x88e6368)
    at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs_build/kio/connection.moc:72
#45 0xb7e46edd in QMetaCallEvent::placeMetaCall (this=0x88d8830, object=0x860fbf8) at kernel/qobject.cpp:535
#46 0xb7e48ba7 in QObject::event (this=0x860fbf8, e=0x88d8830) at kernel/qobject.cpp:1152
#47 0xb599dfab in QApplicationPrivate::notify_helper (this=0x8068a00, receiver=0x860fbf8, e=0x88d8830) at kernel/qapplication.cpp:3809
#48 0xb59a4ae5 in QApplication::notify (this=0xbf93c1e8, receiver=0x860fbf8, e=0x88d8830) at kernel/qapplication.cpp:3399
#49 0xb798a2b1 in KApplication::notify (this=0xbf93c1e8, receiver=0x860fbf8, event=0x88d8830) at /var/tmp/portage/kde-base/kdelibs-4.1.69/work/kdelibs-4.1.69/kdeui/kernel/kapplication.cpp:307
#50 0xb7e38b21 in QCoreApplication::notifyInternal (this=0xbf93c1e8, receiver=0x860fbf8, event=0x88d8830) at kernel/qcoreapplication.cpp:593
#51 0xb7e39984 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x8050490) at kernel/qcoreapplication.h:215
#52 0xb7e39bc3 in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1097
#53 0xb5a335a1 in QEventDispatcherX11::processEvents (this=0x8061ff0, flags={i = -1080835832}) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:220
#54 0xb7e376b0 in QEventLoop::processEvents (this=0xbf93c180, flags={i = -1080835768}) at kernel/qeventloop.cpp:149
#55 0xb7e37852 in QEventLoop::exec (this=0xbf93c180, flags={i = -1080835704}) at kernel/qeventloop.cpp:200
#56 0xb7e39c6f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:851
#57 0xb599dd43 in QApplication::exec () at kernel/qapplication.cpp:3337
#58 0x0804b901 in main (argc=1, argv=0xbf93c3a4) at /var/tmp/portage/kde-base/kontact-4.1.69/work/kontact-4.1.69/kontact/src/main.cpp:218

Reassigning to kdepim-bugs. Looks like a valid bug :)

*** Bug 217068 has been marked as a duplicate of this bug. ***

From bug 216892:
---
Kmail crashed when i tried to change the status of a read mail to new

*** Bug 216892 has been marked as a duplicate of this bug. ***

*** This bug has been marked as a duplicate of bug 191677 ***