Preliminary investigation suggests that this crash only happens with Qt 4.5 (which explains why it wasn't reported earlier).

*** Bug 189332 has been marked as a duplicate of this bug. ***

In addition to only happening with Qt 4.5, this crash also seems to disappear here when Qt is built in debug mode. Hence I've been unable to get a useful backtrace so far.

I've now finally been able to produce a useful backtrace, and the crash does indeed happen inside Qt. I'll investigate further and we'll see whether this ends up being a bug report to Nokia or whether a workaround inside Yakuake is in order.

I can confirm that this indeed happens only with Qt 4.5

Reproduced here, 

rpm -q yakuake
yakuake-2.9.4-2.fc11.i586

on fedora11(beta) with backtrace goodness:

Application: Yakuake (yakuake), signal SIGSEGV
[Current thread is 1 (Thread 0xb8093780 (LWP 4163))]

Thread 2 (Thread 0xb6a27b70 (LWP 4164)):
#0  0x00af9422 in __kernel_vsyscall ()
#1  0x031ec531 in select () from /lib/libc.so.6
#2  0x00c14345 in QProcessManager::run (this=0x9ff91e8) at io/qprocess_unix.cpp:305
#3  0x00b43e8e in QThreadPrivate::start (arg=0x9ff91e8) at thread/qthread_unix.cpp:189
#4  0x00167965 in start_thread (arg=0xb6a27b70) at pthread_create.c:297
#5  0x031f3e7e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb8093780 (LWP 4163)):
[KCrash Handler]
#6  0x0412af12 in QMenu::findIdForAction (this=0xa08e4a8, act=0xa08b1e8) at widgets/qmenu.cpp:3157
#7  0x0412c6dd in QMenuPrivate::activateCausedStack (this=0xa0924d8, causedStack=@0xbfcbd8fc, action=0xa08b1e8, action_e=QAction::Trigger, self=true) at widgets/qmenu.cpp:965
#8  0x04132f8b in QMenuPrivate::activateAction (this=0xa0924d8, action=0xa08b1e8, action_e=QAction::Trigger, self=<value optimized out>) at widgets/qmenu.cpp:1058
#9  0x04133ab7 in QMenu::mouseReleaseEvent (this=0xa08e4a8, e=0xbfcbdf40) at widgets/qmenu.cpp:2252
#10 0x007b4865 in KMenu::mouseReleaseEvent (this=0xa08e4a8, e=0xbfcbdf40) at /usr/src/debug/kdelibs-4.2.2/kdeui/widgets/kmenu.cpp:454
#11 0x03d08487 in QWidget::event (this=0xa08e4a8, event=0xbfcbdf40) at kernel/qwidget.cpp:7516
#12 0x04135dbc in QMenu::event (this=0xa08e4a8, e=0xbfcbdf40) at widgets/qmenu.cpp:2351
#13 0x03cb2cfc in QApplicationPrivate::notify_helper (this=0x9ffe3d0, receiver=0xa08e4a8, e=0xbfcbdf40) at kernel/qapplication.cpp:4084
#14 0x03cba9fb in QApplication::notify (this=0xbfcbf98c, receiver=0xa08e4a8, e=0xbfcbdf40) at kernel/qapplication.cpp:3786
#15 0x006d0fda in KApplication::notify (this=0xbfcbf98c, receiver=0xa08e4a8, event=0xbfcbdf40) at /usr/src/debug/kdelibs-4.2.2/kdeui/kernel/kapplication.cpp:307
#16 0x00c366db in QCoreApplication::notifyInternal (this=0xbfcbf98c, receiver=0xa08e4a8, event=0xbfcbdf40) at kernel/qcoreapplication.cpp:602
#17 0x03cb9a7e in QCoreApplication::sendSpontaneousEvent (event=<value optimized out>, receiver=<value optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:216
#18 QApplicationPrivate::sendMouseEvent (event=<value optimized out>, receiver=<value optimized out>) at kernel/qapplication.cpp:2940
#19 0x03d2912f in QETWidget::translateMouseEvent (this=0xa08e4a8, event=0xbfcbe53c) at kernel/qapplication_x11.cpp:4359
#20 0x03d280f2 in QApplication::x11ProcessEvent (this=0xbfcbf98c, event=0xbfcbe53c) at kernel/qapplication_x11.cpp:3421
#21 0x03d53142 in x11EventSourceDispatch (s=0x9fffbe8, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#22 0x07acc1e8 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#23 0x07acf7f8 in ?? () from /lib/libglib-2.0.so.0
#24 0x07acf96a in g_main_context_iteration () from /lib/libglib-2.0.so.0
#25 0x00c61bcc in QEventDispatcherGlib::processEvents (this=0x9fced68, flags={i = 36}) at kernel/qeventdispatcher_glib.cpp:323
#26 0x03d52825 in QGuiEventDispatcherGlib::processEvents (this=0x9fced68, flags={i = 36}) at kernel/qguieventdispatcher_glib.cpp:202
#27 0x00c34c69 in QEventLoop::processEvents (this=0xbfcbe830, flags=) at kernel/qeventloop.cpp:149
#28 0x00c350b2 in QEventLoop::exec (this=0xbfcbe830, flags={i = 0}) at kernel/qeventloop.cpp:200
#29 0x04135c0e in QMenu::exec (this=0xa071fd0, p=@0xbfcbe8cc, action=0x0) at widgets/qmenu.cpp:1991
#30 0x041422da in QPushButtonPrivate::_q_popupPressed (this=0xa08a450) at widgets/qpushbutton.cpp:611
#31 0x04143958 in QPushButton::qt_metacall (this=0xa079b38, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0xbfcbe9cc) at .moc/release-shared/moc_qpushbutton.cpp:74
#32 0x007c1f8a in KPushButton::qt_metacall (this=0xa079b38, _c=QMetaObject::InvokeMetaMethod, _id=40, _a=0xbfcbe9cc) at /usr/src/debug/kdelibs-4.2.2/i586-redhat-linux-gnu/kdeui/kpushbutton.moc:70
#33 0x00c4c948 in QMetaObject::activate (sender=0xa079b38, from_signal_index=27, to_signal_index=27, argv=0x0) at kernel/qobject.cpp:3069
#34 0x00c4d5e2 in QMetaObject::activate (sender=0xa079b38, m=0x4553804, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3143
#35 0x0436f547 in QAbstractButton::pressed (this=0xa079b38) at .moc/release-shared/moc_qabstractbutton.cpp:187
#36 0x04097ac9 in QAbstractButtonPrivate::emitPressed (this=0xa08a450) at widgets/qabstractbutton.cpp:557
#37 0x04097cc1 in QAbstractButton::mousePressEvent (this=0xa079b38, e=0xbfcbeff0) at widgets/qabstractbutton.cpp:1092
#38 0x007c1bc1 in KPushButton::mousePressEvent (this=0x6, e=0xa08b1e8) at /usr/src/debug/kdelibs-4.2.2/kdeui/widgets/kpushbutton.cpp:226
#39 0x03d0846b in QWidget::event (this=0xa079b38, event=0xbfcbeff0) at kernel/qwidget.cpp:7512
#40 0x04097dce in QAbstractButton::event (this=0xa079b38, e=0xa08b1e8) at widgets/qabstractbutton.cpp:1077
#41 0x0414378d in QPushButton::event (this=0xa079b38, e=0xbfcbeff0) at widgets/qpushbutton.cpp:662
#42 0x03cb2cfc in QApplicationPrivate::notify_helper (this=0x9ffe3d0, receiver=0xa079b38, e=0xbfcbeff0) at kernel/qapplication.cpp:4084
#43 0x03cba9fb in QApplication::notify (this=0xbfcbf98c, receiver=0xa079b38, e=0xbfcbeff0) at kernel/qapplication.cpp:3786
#44 0x006d0fda in KApplication::notify (this=0xbfcbf98c, receiver=0xa079b38, event=0xbfcbeff0) at /usr/src/debug/kdelibs-4.2.2/kdeui/kernel/kapplication.cpp:307
#45 0x00c366db in QCoreApplication::notifyInternal (this=0xbfcbf98c, receiver=0xa079b38, event=0xbfcbeff0) at kernel/qcoreapplication.cpp:602
#46 0x03cb9a7e in QCoreApplication::sendSpontaneousEvent (event=<value optimized out>, receiver=<value optimized out>) at ../../src/corelib/kernel/qcoreapplication.h:216
#47 QApplicationPrivate::sendMouseEvent (event=<value optimized out>, receiver=<value optimized out>) at kernel/qapplication.cpp:2940
#48 0x03d28c40 in QETWidget::translateMouseEvent (this=0xa075018, event=0xbfcbf5ec) at kernel/qapplication_x11.cpp:4425
#49 0x03d280f2 in QApplication::x11ProcessEvent (this=0xbfcbf98c, event=0xbfcbf5ec) at kernel/qapplication_x11.cpp:3421
#50 0x03d53142 in x11EventSourceDispatch (s=0x9fffbe8, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#51 0x07acc1e8 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#52 0x07acf7f8 in ?? () from /lib/libglib-2.0.so.0
#53 0x07acf96a in g_main_context_iteration () from /lib/libglib-2.0.so.0
#54 0x00c61bcc in QEventDispatcherGlib::processEvents (this=0x9fced68, flags={i = 36}) at kernel/qeventdispatcher_glib.cpp:323
#55 0x03d52825 in QGuiEventDispatcherGlib::processEvents (this=0x9fced68, flags={i = 36}) at kernel/qguieventdispatcher_glib.cpp:202
#56 0x00c34c69 in QEventLoop::processEvents (this=0xbfcbf8e4, flags=) at kernel/qeventloop.cpp:149
#57 0x00c350b2 in QEventLoop::exec (this=0xbfcbf8e4, flags={i = 0}) at kernel/qeventloop.cpp:200
#58 0x00c3743f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:880
#59 0x03cb2b77 in QApplication::exec () at kernel/qapplication.cpp:3553
#60 0x08056aa7 in main (argc=1, argv=0xbfcbfae4) at /usr/src/debug/yakuake-2.9.4/app/main.cpp:82

Sorry, turns out I attached the fix message to the wrong bug (bug 189332, the duplicate). This bug is fixed in SVN since r952380 / April 11th, and a 2.9.5 release containing this and other fixes is planned for the first week of May (string freeze went into effect yesterday).

*** Bug 201590 has been marked as a duplicate of this bug. ***

*** Bug 202350 has been marked as a duplicate of this bug. ***