Application that crashed: plasma-desktop
Version of the application: 0.3
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.31-14-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
I had just upgraded to Unbuntu 9.10 the previous day. This was the second login after the upgrade and restart completed. I left it running overnight as a test. This morning, the desktop had dissappeared and the only way I could recover was to use Ctrl+Alt+F1, log in and issue an "sudo reboot" command. 

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb7732700 (LWP 2750))]

Thread 3 (Thread 0xac513b70 (LWP 2751)):
#0  0x00d67422 in __kernel_vsyscall ()
#1  0x00570e15 in pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_wait.S:122
#2  0x00be678d in __pthread_cond_wait (cond=0x9b4a368, mutex=0x9b4a350) at forward.c:139
#3  0x007eae67 in QWaitConditionPrivate::wait (this=0x9bac768, mutex=0x9bac764, time=4294967295) at thread/qwaitcondition_unix.cpp:87
#4  QWaitCondition::wait (this=0x9bac768, mutex=0x9bac764, time=4294967295) at thread/qwaitcondition_unix.cpp:159
#5  0x00ccb922 in QHostInfoAgent::run (this=0x9bac758) at kernel/qhostinfo.cpp:260
#6  0x007e9e32 in QThreadPrivate::start (arg=0x9bac758) at thread/qthread_unix.cpp:188
#7  0x0056c80e in start_thread (arg=0xac513b70) at pthread_create.c:300
#8  0x00bd97ee in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 2 (Thread 0xa7019b70 (LWP 2752)):
#0  0x00d67422 in __kernel_vsyscall ()
#1  0x00571142 in pthread_cond_timedwait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_timedwait.S:179
#2  0x00be67e4 in __pthread_cond_timedwait (cond=0xa70191f4, mutex=0xa7019224, abstime=0xa7019270) at forward.c:152
#3  0x007e981e in thread_sleep (ti=0x1) at thread/qthread_unix.cpp:297
#4  0x007e9973 in QThread::msleep (msecs=50) at thread/qthread_unix.cpp:323
#5  0x0239276b in ?? () from /usr/lib/kde4/plasma_applet_cwp.so
#6  0x007e9e32 in QThreadPrivate::start (arg=0x9ca2ed0) at thread/qthread_unix.cpp:188
#7  0x0056c80e in start_thread (arg=0xa7019b70) at pthread_create.c:300
#8  0x00bd97ee in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb7732700 (LWP 2750)):
[KCrash Handler]
#6  0x00000000 in ?? ()
#7  0x057de540 in blend_transformed_tiled_argb<(SpanMethod)0> (count=180104200, spans=0xbfc1f7a4, userData=0xabc2c08) at painting/qdrawhelper.cpp:6343
#8  0x057ccfd0 in qBlendTexture (count=256, spans=0xbfc1f7a4, userData=0xabc2c08) at painting/qdrawhelper.cpp:7029
#9  0x057925ea in QSpanBuffer::flushSpans (d=..., allVertical=...) at painting/qrasterizer.cpp:105
#10 QSpanBuffer::addSpan (d=..., allVertical=...) at painting/qrasterizer.cpp:99
#11 qScanConvert<QBoolToType<true> > (d=..., allVertical=...) at painting/qrasterizer.cpp:350
#12 0x0578e58e in QScanConverter::end (this=0xa96a4e4) at painting/qrasterizer.cpp:383
#13 0x05791e39 in QRasterizer::rasterize (this=0xba99170, path=..., fillRule=Qt::OddEvenFill) at painting/qrasterizer.cpp:1246
#14 0x057ba303 in QRasterPaintEngine::fillPath (this=0xa8307a8, path=..., fillData=0xabc2c08) at painting/qpaintengine_raster.cpp:1398
#15 0x057c7049 in QRasterPaintEngine::drawPath (this=0xa8307a8, path=...) at painting/qpaintengine_raster.cpp:1933
#16 0x05752c0f in QPainter::drawPath (this=0xbfc2057c, path=...) at painting/qpainter.cpp:3214
#17 0x0574d09a in QPainterPrivate::draw_helper (this=0xabd31d0, originalPath=..., op=<value optimized out>) at painting/qpainter.cpp:451
#18 0x057500e3 in QPainter::drawRects (this=0xbfc208cc, rects=0xbfc206e8, rectCount=1) at painting/qpainter.cpp:3355
#19 0x05752491 in QPainter::drawRect (this=0xbfc208cc, r=..., pm=..., sr=...) at ../../include/QtGui/../../src/gui/painting/qpainter.h:604
#20 QPainter::drawPixmap (this=0xbfc208cc, r=..., pm=..., sr=...) at painting/qpainter.cpp:5357
#21 0x04677a3c in Plasma::FrameSvg::paintFrame (this=0xbc01b38, painter=0xbfc208cc, target=..., source=...) at ../../plasma/framesvg.cpp:370
#22 0x0465f550 in Plasma::Dialog::paintEvent (this=0x988a078, e=0xbfc20d94) at ../../plasma/dialog.cpp:293
#23 0x0566fdd4 in QWidget::event (this=0x988a078, event=0xbfc20d94) at kernel/qwidget.cpp:7687
#24 0x0465f2c3 in Plasma::Dialog::event (this=0x988a078, event=0xbfc20d94) at ../../plasma/dialog.cpp:397
#25 0x0561af54 in QApplicationPrivate::notify_helper (this=0x9314cf0, receiver=0x988a078, e=0xbfc20d94) at kernel/qapplication.cpp:4056
#26 0x056225ca in QApplication::notify (this=0x92ede60, receiver=0x988a078, e=0xbfc20d94) at kernel/qapplication.cpp:4021
#27 0x0370dbfa in KApplication::notify (this=0x92ede60, receiver=0x988a078, event=0xbfc20d94) at ../../kdeui/kernel/kapplication.cpp:302
#28 0x008da6cb in QCoreApplication::notifyInternal (this=0x92ede60, receiver=0x988a078, event=0xbfc20d94) at kernel/qcoreapplication.cpp:610
#29 0x05677e25 in QCoreApplication::sendSpontaneousEvent (this=0xbc01a18, pdev=0xbb2376c, rgn=..., offset=..., flags=<value optimized out>, sharedPainter=0x0, backingStore=0x9b9c820)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#30 QWidgetPrivate::drawWidget (this=0xbc01a18, pdev=0xbb2376c, rgn=..., offset=..., flags=<value optimized out>, sharedPainter=0x0, backingStore=0x9b9c820) at kernel/qwidget.cpp:5079
#31 0x058062f8 in QWidgetBackingStore::sync (this=0x9b9c820) at painting/qbackingstore.cpp:1269
#32 0x05669116 in QWidgetPrivate::syncBackingStore (this=0xbc01a18) at kernel/qwidget.cpp:1603
#33 0x05670215 in QWidget::event (this=0x988a078, event=0xa5b1ad0) at kernel/qwidget.cpp:7827
#34 0x0465f2c3 in Plasma::Dialog::event (this=0x988a078, event=0xa5b1ad0) at ../../plasma/dialog.cpp:397
#35 0x0561af54 in QApplicationPrivate::notify_helper (this=0x9314cf0, receiver=0x988a078, e=0xa5b1ad0) at kernel/qapplication.cpp:4056
#36 0x056225ca in QApplication::notify (this=0x92ede60, receiver=0x988a078, e=0xa5b1ad0) at kernel/qapplication.cpp:4021
#37 0x0370dbfa in KApplication::notify (this=0x92ede60, receiver=0x988a078, event=0xa5b1ad0) at ../../kdeui/kernel/kapplication.cpp:302
#38 0x008da6cb in QCoreApplication::notifyInternal (this=0x92ede60, receiver=0x988a078, event=0xa5b1ad0) at kernel/qcoreapplication.cpp:610
#39 0x008db2b2 in QCoreApplication::sendEvent (receiver=0x0, event_type=0, data=0x9285e48) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#40 QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x9285e48) at kernel/qcoreapplication.cpp:1247
#41 0x008db47d in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1140
#42 0x009053ff in QCoreApplication::sendPostedEvents (s=0x9316d10) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:218
#43 postEventSourceDispatch (s=0x9316d10) at kernel/qeventdispatcher_glib.cpp:210
#44 0x00293e78 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#45 0x00297720 in ?? () from /lib/libglib-2.0.so.0
#46 0x00297853 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#47 0x0090502c in QEventDispatcherGlib::processEvents (this=0x9314ab0, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#48 0x056bbbe5 in QGuiEventDispatcherGlib::processEvents (this=0x9314ab0, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#49 0x008d8c79 in QEventLoop::processEvents (this=0xbfc21864, flags=) at kernel/qeventloop.cpp:149
#50 0x008d90ca in QEventLoop::exec (this=0xbfc21864, flags=...) at kernel/qeventloop.cpp:201
#51 0x008db53f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#52 0x0561add7 in QApplication::exec () at kernel/qapplication.cpp:3525
#53 0x05f6480d in kdemain () from /usr/lib/libkdeinit4_plasma-desktop.so
#54 0x0804dde1 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x929f278 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x80511a5 "0") at ../../kinit/kinit.cpp:677
#55 0x0804ea35 in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#56 0x0804eeac in handle_requests (waitForPid=<value optimized out>) at ../../kinit/kinit.cpp:1362
#57 0x0804fbaf in main (argc=2, argv=0xbfc220c4, envp=0xbfc220d0) at ../../kinit/kinit.cpp:1793

Reported using DrKonqi