Application: konqueror (4.14.2)
KDE Platform Version: 4.14.2
Qt Version: 4.8.7
Operating System: Linux 4.0.0-2-686-pae i686
Distribution: Debian GNU/Linux testing/unstable (stretch)

-- Information about the crash:
Could this be caused by a failing processor? I have been getting rare random GUI glitches & segfaults since a couple of months.. My 8GB of RAM also have two faulty bits (since a year or so, verified recently with memtest86), but I told the kernel to ignore them (memmap=129m$1684m) so in theory, it shouldn't cause issues.
Just about to replace CPU & mainboard, but still interested in the definite cause of this.

The crash can be reproduced sometimes.

-- Backtrace:
Application: Konqueror (konqueror), signal: Segmentation fault
Using host libthread_db library "/lib/i386-linux-gnu/i686/cmov/libthread_db.so.1".
[Current thread is 1 (Thread 0xb2c5a7c0 (LWP 21429))]

Thread 3 (Thread 0xabe64b40 (LWP 21512)):
#0  0xffffffff in __kernel_vsyscall ()
#1  0xffffffff in __GI___clock_gettime (clock_id=1, tp=0xabe63f84) at ../sysdeps/unix/clock_gettime.c:115
#2  0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#3  0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#4  0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#5  0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#6  0xffffffff in g_main_context_prepare (context=<optimized out>, priority=0xabe640d4) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3410
#7  0xffffffff in g_main_context_iterate (context=context@entry=0xab5004e0, block=block@entry=1, dispatch=1, self=<optimized out>) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3788
#8  0xffffffff in g_main_context_iteration (context=0xab5004e0, may_block=1) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3869
#9  0xffffffff in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0xffffffff in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#11 0xffffffff in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#12 0xffffffff in QThread::exec() () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#13 0xffffffff in QThread::run() () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#14 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#15 0xffffffff in start_thread (arg=0xabe64b40) at pthread_create.c:309
#16 0xffffffff in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:129

Thread 2 (Thread 0xaaaffb40 (LWP 21556)):
#0  0xffffffff in __kernel_vsyscall ()
#1  0xffffffff in read () at ../sysdeps/unix/syscall-template.S:81
#2  0xffffffff in g_wakeup_acknowledge (__nbytes=16, __buf=0xaaafeffc, __fd=<optimized out>) at /usr/include/i386-linux-gnu/bits/unistd.h:44
#3  0xffffffff in g_wakeup_acknowledge (wakeup=0xaab01db8) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gwakeup.c:210
#4  0xffffffff in g_main_context_check (context=0xaa1004e0, max_priority=2147483647, fds=0xaa1027a8, n_fds=1) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3600
#5  0xffffffff in g_main_context_iterate (context=context@entry=0xaa1004e0, block=block@entry=1, dispatch=1, self=<optimized out>) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3805
#6  0xffffffff in g_main_context_iteration (context=0xaa1004e0, may_block=1) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3869
#7  0xffffffff in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#8  0xffffffff in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#9  0xffffffff in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0xffffffff in QThread::exec() () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#11 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#12 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#13 0xffffffff in start_thread (arg=0xaaaffb40) at pthread_create.c:309
#14 0xffffffff in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:129

Thread 1 (Thread 0xb2c5a7c0 (LWP 21429)):
[KCrash Handler]
#7  0xffffffff in do_sin (x=x@entry=0.7853981633974485, dx=2.2884754904439333e-17, dx@entry=0.7853981633974485, corp=corp@entry=0xbffb3ca0, u=...) at ../sysdeps/ieee754/dbl-64/s_sin.c:208
#8  0xffffffff in __sin (x=x@entry=5.497787143782138) at ../sysdeps/ieee754/dbl-64/s_sin.c:389
#9  0xffffffff in __sincos (x=5.497787143782138, sinx=0xbffb3d58, cosx=0xbffb3d50) at ../sysdeps/ieee754/dbl-64/s_sincos.c:42
#10 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#11 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#12 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#13 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#14 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#15 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#16 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#17 0xffffffff in  () at /usr/lib/i386-linux-gnu/libcairo.so.2
#18 0xffffffff in cairo_stroke () at /usr/lib/i386-linux-gnu/libcairo.so.2
#19 0xffffffff in  () at /usr/lib/i386-linux-gnu/gtk-2.0/2.10.0/engines/libmurrine.so
#20 0xffffffff in  () at /usr/lib/i386-linux-gnu/gtk-2.0/2.10.0/engines/libmurrine.so
#21 0xffffffff in  () at /usr/lib/i386-linux-gnu/gtk-2.0/2.10.0/engines/libmurrine.so
#22 0xffffffff in gtk_paint_box () at /usr/lib/i386-linux-gnu/libgtk-x11-2.0.so.0
#23 0xffffffff in  () at /usr/lib/i386-linux-gnu/libgtk-x11-2.0.so.0
#24 0xffffffff in  () at /usr/lib/i386-linux-gnu/gtk-2.0/2.10.0/engines/libmurrine.so
#25 0xffffffff in gtk_paint_slider () at /usr/lib/i386-linux-gnu/libgtk-x11-2.0.so.0
#26 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#27 0xffffffff in QGtkStyle::drawComplexControl(QStyle::ComplexControl, QStyleOptionComplex const*, QPainter*, QWidget const*) const () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#28 0xffffffff in QScrollBar::paintEvent(QPaintEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#29 0xffffffff in QWidget::event(QEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#30 0xffffffff in QAbstractSlider::event(QEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#31 0xffffffff in QScrollBar::event(QEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#32 0xffffffff in QApplicationPrivate::notify_helper(QObject*, QEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#33 0xffffffff in QApplication::notify(QObject*, QEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#34 0xffffffff in KApplication::notify(QObject*, QEvent*) () at /usr/lib/libkdeui.so.5
#35 0xffffffff in QCoreApplication::notifyInternal(QObject*, QEvent*) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#36 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#37 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#38 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#39 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#40 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#41 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#42 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#43 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#44 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#45 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#46 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#47 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#48 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#49 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#50 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#51 0xffffffff in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#52 0xffffffff in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#53 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#54 0xffffffff in QWidgetPrivate::syncBackingStore() () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#55 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#56 0xffffffff in QApplication::x11ProcessEvent(_XEvent*) () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#57 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#58 0xffffffff in g_main_context_dispatch (context=0x97ce720) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3122
#59 0xffffffff in g_main_context_dispatch (context=0x97ce720) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3737
#60 0xffffffff in g_main_context_iterate (context=context@entry=0x97ce720, block=block@entry=1, dispatch=1, self=<optimized out>) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3808
#61 0xffffffff in g_main_context_iteration (context=0x97ce720, may_block=1) at /build/glib2.0-dCKQ11/glib2.0-2.44.1/./glib/gmain.c:3869
#62 0xffffffff in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#63 0xffffffff in  () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#64 0xffffffff in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#65 0xffffffff in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#66 0xffffffff in QCoreApplication::exec() () at /usr/lib/i386-linux-gnu/libQtCore.so.4
#67 0xffffffff in QApplication::exec() () at /usr/lib/i386-linux-gnu/libQtGui.so.4
#68 0xffffffff in kdemain () at /usr/lib/kde4/libkdeinit/libkdeinit4_konqueror.so
#69 0x0804856b in  ()
#70 0xffffffff in __libc_start_main (main=0x8048550, argc=2, argv=0xbffb8104, init=0x8048680 <__libc_csu_init>, fini=0x80486f0 <__libc_csu_fini>, rtld_fini=0xb7777c90 <_dl_fini>, stack_end=0xbffb80fc) at libc-start.c:287
#71 0x08048597 in _start ()

Reported using DrKonqi