Two separate crashes' backtraces listed here:

Crash (A):

Application: KMail (kmail), signal SIGABRT
0x00000033d0ea86e1 in nanosleep () from /lib/libc.so.6
[Current thread is 0 (LWP 20465)]

Thread 2 (Thread 0x4225f950 (LWP 20484)):
#0  0x00000033d0edf4b2 in select () from /lib/libc.so.6
#1  0x00000037b7d35006 in ?? () from /usr/lib/libQtCore.so.4
#2  0x00000037b7c6c362 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00000033d1a073ea in start_thread () from /lib/libpthread.so.0
#4  0x00000033d0ee6cbd in clone () from /lib/libc.so.6
#5  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f23ed2a76f0 (LWP 20465)):
[KCrash Handler]
#5  0x00000033d0e33015 in raise () from /lib/libc.so.6
#6  0x00000033d0e34b83 in abort () from /lib/libc.so.6
#7  0x00000037b7c646b5 in qt_message_output () from /usr/lib/libQtCore.so.4
#8  0x00000037b7c647fd in qFatal () from /usr/lib/libQtCore.so.4
#9  0x0000003573bff681 in ?? () from /usr/lib/libkmailprivate.so.4
#10 0x0000003573bfe111 in ?? () from /usr/lib/libkmailprivate.so.4
#11 0x0000003573c47fe6 in ?? () from /usr/lib/libkmailprivate.so.4
#12 0x0000003573bfdb99 in ?? () from /usr/lib/libkmailprivate.so.4
#13 0x0000003573df12c6 in ?? () from /usr/lib/libkmailprivate.so.4
#14 0x0000003573df1438 in ?? () from /usr/lib/libkmailprivate.so.4
#15 0x00000037b7d69134 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0x00000037b7d63a43 in QObject::event () from /usr/lib/libQtCore.so.4
#17 0x00000037b95cac3d in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#18 0x00000037b95d29ba in QApplication::notify () from /usr/lib/libQtGui.so.4
#19 0x00000037ef6065db in KApplication::notify (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>)
    at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#20 0x00000037b7d54d61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#21 0x00000037b7d80ab6 in ?? () from /usr/lib/libQtCore.so.4
#22 0x00000037b7d7d1fd in ?? () from /usr/lib/libQtCore.so.4
#23 0x00000037b7039d3b in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#24 0x00000037b703d50d in ?? () from /usr/lib/libglib-2.0.so.0
#25 0x00000037b703d6cb in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#26 0x00000037b7d7d15f in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#27 0x00000037b965ca6f in ?? () from /usr/lib/libQtGui.so.4
#28 0x00000037b7d53682 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#29 0x00000037b7d5380d in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#30 0x00000037b7d55cbd in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#31 0x000000000040309b in _start ()


Crash (B):

Application: KMail (kmail), signal SIGABRT
0x00000033d0ea86e1 in nanosleep () from /lib/libc.so.6
[Current thread is 0 (LWP 22039)]

Thread 3 (Thread 0x427fe950 (LWP 22082)):
#0  0x00000033d0edf4b2 in select () from /lib/libc.so.6
#1  0x00000037b7d35006 in ?? () from /usr/lib/libQtCore.so.4
#2  0x00000037b7c6c362 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00000033d1a073ea in start_thread () from /lib/libpthread.so.0
#4  0x00000033d0ee6cbd in clone () from /lib/libc.so.6
#5  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x41ffd950 (LWP 22272)):
#0  0x00000033d1a0b55d in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00000037b7c6d327 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#2  0x00000037b7c63509 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00000037b7c6c362 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00000033d1a073ea in start_thread () from /lib/libpthread.so.0
#5  0x00000033d0ee6cbd in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fbc674fb6f0 (LWP 22039)):
[KCrash Handler]
#5  0x00000033d0e33015 in raise () from /lib/libc.so.6
#6  0x00000033d0e34b83 in abort () from /lib/libc.so.6
#7  0x00000037b7c646b5 in qt_message_output () from /usr/lib/libQtCore.so.4
#8  0x00000037b7c647fd in qFatal () from /usr/lib/libQtCore.so.4
#9  0x0000003573bff681 in ?? () from /usr/lib/libkmailprivate.so.4
#10 0x0000003573bfe111 in ?? () from /usr/lib/libkmailprivate.so.4
#11 0x0000003573c47fe6 in ?? () from /usr/lib/libkmailprivate.so.4
#12 0x0000003573bfdb99 in ?? () from /usr/lib/libkmailprivate.so.4
#13 0x0000003573df12c6 in ?? () from /usr/lib/libkmailprivate.so.4
#14 0x0000003573df1438 in ?? () from /usr/lib/libkmailprivate.so.4
#15 0x00000037b7d69134 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0x00000037b7d63a43 in QObject::event () from /usr/lib/libQtCore.so.4
#17 0x00000037b95cac3d in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#18 0x00000037b95d29ba in QApplication::notify () from /usr/lib/libQtGui.so.4
#19 0x00000037ef6065db in KApplication::notify (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>)
    at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#20 0x00000037b7d54d61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#21 0x00000037b7d80ab6 in ?? () from /usr/lib/libQtCore.so.4
#22 0x00000037b7d7d1fd in ?? () from /usr/lib/libQtCore.so.4
#23 0x00000037b7039d3b in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#24 0x00000037b703d50d in ?? () from /usr/lib/libglib-2.0.so.0
#25 0x00000037b703d6cb in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#26 0x00000037b7d7d15f in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#27 0x00000037b965ca6f in ?? () from /usr/lib/libQtGui.so.4
#28 0x00000037b7d53682 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#29 0x00000037b7d5380d in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#30 0x00000037b7d55cbd in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#31 0x000000000040309b in _start ()

Crash (B):

Application: KMail (kmail), signal SIGABRT
0x00000033d0ea86e1 in nanosleep () from /lib/libc.so.6
[Current thread is 0 (LWP 22039)]

Thread 3 (Thread 0x427fe950 (LWP 22082)):
#0  0x00000033d0edf4b2 in select () from /lib/libc.so.6
#1  0x00000037b7d35006 in ?? () from /usr/lib/libQtCore.so.4
#2  0x00000037b7c6c362 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00000033d1a073ea in start_thread () from /lib/libpthread.so.0
#4  0x00000033d0ee6cbd in clone () from /lib/libc.so.6
#5  0x0000000000000000 in ?? ()

Thread 2 (Thread 0x41ffd950 (LWP 22272)):
#0  0x00000033d1a0b55d in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00000037b7c6d327 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#2  0x00000037b7c63509 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00000037b7c6c362 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00000033d1a073ea in start_thread () from /lib/libpthread.so.0
#5  0x00000033d0ee6cbd in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7fbc674fb6f0 (LWP 22039)):
[KCrash Handler]
#5  0x00000033d0e33015 in raise () from /lib/libc.so.6
#6  0x00000033d0e34b83 in abort () from /lib/libc.so.6
#7  0x00000037b7c646b5 in qt_message_output () from /usr/lib/libQtCore.so.4
#8  0x00000037b7c647fd in qFatal () from /usr/lib/libQtCore.so.4
#9  0x0000003573bff681 in ?? () from /usr/lib/libkmailprivate.so.4
#10 0x0000003573bfe111 in ?? () from /usr/lib/libkmailprivate.so.4
#11 0x0000003573c47fe6 in ?? () from /usr/lib/libkmailprivate.so.4
#12 0x0000003573bfdb99 in ?? () from /usr/lib/libkmailprivate.so.4
#13 0x0000003573df12c6 in ?? () from /usr/lib/libkmailprivate.so.4
#14 0x0000003573df1438 in ?? () from /usr/lib/libkmailprivate.so.4
#15 0x00000037b7d69134 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0x00000037b7d63a43 in QObject::event () from /usr/lib/libQtCore.so.4
#17 0x00000037b95cac3d in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#18 0x00000037b95d29ba in QApplication::notify () from /usr/lib/libQtGui.so.4
#19 0x00000037ef6065db in KApplication::notify (this=<value optimized out>, receiver=<value optimized out>, event=<value optimized out>)
    at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#20 0x00000037b7d54d61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#21 0x00000037b7d80ab6 in ?? () from /usr/lib/libQtCore.so.4
#22 0x00000037b7d7d1fd in ?? () from /usr/lib/libQtCore.so.4
#23 0x00000037b7039d3b in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#24 0x00000037b703d50d in ?? () from /usr/lib/libglib-2.0.so.0
#25 0x00000037b703d6cb in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#26 0x00000037b7d7d15f in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#27 0x00000037b965ca6f in ?? () from /usr/lib/libQtGui.so.4
#28 0x00000037b7d53682 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#29 0x00000037b7d5380d in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#30 0x00000037b7d55cbd in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#31 0x000000000040309b in _start ()