Version:            (using KDE 4.2.0)
OS:                Linux
Installed from:    Ubuntu Packages

Plasma crashed with SIGSEGV. I wasn't doing anything peculiar at the time.
Prior to the crash, panel elements started having black backgrounds progressively (task manager, clock, etc)

My nvidia driver version is 180.29.

Backtrace:

Application: Plasma Workspace (plasma), signal SIGSEGV
[Current thread is 0 (LWP 6134)]

Thread 4 (Thread 0xa8d6eb90 (LWP 6138)):
#0  0xb8098430 in __kernel_vsyscall ()
#1  0xb6501df1 in select () from /lib/tls/i686/cmov/libc.so.6
#2  0xb67d0150 in ?? () from /usr/lib/libQtCore.so.4
#3  0xb67006ae in ?? () from /usr/lib/libQtCore.so.4
#4  0xb58f150f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#5  0xb6509a0e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 3 (Thread 0xa8557b90 (LWP 6140)):
#0  0xb8098430 in __kernel_vsyscall ()
#1  0xb58f5075 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb6517bbd in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb67016f2 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#4  0xb7a5a532 in ?? () from /usr/lib/libQtNetwork.so.4
#5  0xb67006ae in ?? () from /usr/lib/libQtCore.so.4
#6  0xb58f150f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb6509a0e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 2 (Thread 0xa7ca4b90 (LWP 6141)):
#0  0xb8098430 in __kernel_vsyscall ()
#1  0xb58f5075 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0xb6517bbd in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0xb67016f2 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#4  0xa8fc6c8a in RenderThread::run (this=0x8f30574) at /build/buildd/kdebase-workspace-4.2.0/plasma/wallpapers/image/renderthread.cpp:91
#5  0xb67006ae in ?? () from /usr/lib/libQtCore.so.4
#6  0xb58f150f in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#7  0xb6509a0e in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb4569900 (LWP 6134)):
[KCrash Handler]
#6  0xb6b2e661 in QImage::scanLine () from /usr/lib/libQtGui.so.4
#7  0xb6b0b640 in QWidgetPrivate::setWindowIcon_sys () from /usr/lib/libQtGui.so.4
#8  0xb6ad649b in QWidget::create () from /usr/lib/libQtGui.so.4
#9  0xb6ad22f3 in QWidgetPrivate::createWinId () from /usr/lib/libQtGui.so.4
#10 0xb6ad5fa8 in QWidget::createWinId () from /usr/lib/libQtGui.so.4
#11 0xb6e5b052 in QMenu::exec () from /usr/lib/libQtGui.so.4
#12 0xa91414dc in WindowTaskItem::contextMenuEvent (this=0x9cf8fb8, e=0xbfd970bc) at /build/buildd/kdebase-workspace-4.2.0/plasma/applets/tasks/windowtaskitem.cpp:276
#13 0xb6ffd07e in QGraphicsItem::sceneEvent () from /usr/lib/libQtGui.so.4
#14 0xb70407af in QGraphicsWidget::sceneEvent () from /usr/lib/libQtGui.so.4
#15 0xb701b54c in ?? () from /usr/lib/libQtGui.so.4
#16 0xb7021907 in QGraphicsScene::contextMenuEvent () from /usr/lib/libQtGui.so.4
#17 0xb7024747 in QGraphicsScene::event () from /usr/lib/libQtGui.so.4
#18 0xb6a808ec in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#19 0xb6a8872e in QApplication::notify () from /usr/lib/libQtGui.so.4
#20 0xb77e4fed in KApplication::notify (this=0x8d4bd90, receiver=0x8dcdb40, event=0xbfd970bc) at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#21 0xb67f0e61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#22 0xb70314c6 in QGraphicsView::contextMenuEvent () from /usr/lib/libQtGui.so.4
#23 0xb6ad8c6d in QWidget::event () from /usr/lib/libQtGui.so.4
#24 0xb6e0ffd3 in QFrame::event () from /usr/lib/libQtGui.so.4
#25 0xb6ea67df in QAbstractScrollArea::viewportEvent () from /usr/lib/libQtGui.so.4
#26 0xb7033d0f in QGraphicsView::viewportEvent () from /usr/lib/libQtGui.so.4
#27 0xb6ea8d85 in ?? () from /usr/lib/libQtGui.so.4
#28 0xb67f004a in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib/libQtCore.so.4
#29 0xb6a808ca in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#30 0xb6a88c55 in QApplication::notify () from /usr/lib/libQtGui.so.4
#31 0xb77e4fed in KApplication::notify (this=0x8d4bd90, receiver=0x90ec420, event=0xbfd976c0) at /build/buildd/kde4libs-4.2.0/kdeui/kernel/kapplication.cpp:307
#32 0xb67f0e61 in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#33 0xb6a8b86e in QCoreApplication::sendSpontaneousEvent () from /usr/lib/libQtGui.so.4
#34 0xb6af2e3f in ?? () from /usr/lib/libQtGui.so.4
#35 0xb6af19e5 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#36 0xb6b1b7aa in ?? () from /usr/lib/libQtGui.so.4
#37 0xb57366f8 in IA__g_main_context_dispatch (context=0x8d66a98) at /build/buildd/glib2.0-2.18.2/glib/gmain.c:2144
#38 0xb5739da3 in g_main_context_iterate (context=0x8d66a98, block=1, dispatch=1, self=0x8d637c8) at /build/buildd/glib2.0-2.18.2/glib/gmain.c:2778
#39 0xb5739f61 in IA__g_main_context_iteration (context=0x8d66a98, may_block=1) at /build/buildd/glib2.0-2.18.2/glib/gmain.c:2841
#40 0xb681b478 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#41 0xb6b1aea5 in ?? () from /usr/lib/libQtGui.so.4
#42 0xb67ef52a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#43 0xb67ef6ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#44 0xb67f1da5 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#45 0xb6a80767 in QApplication::exec () from /usr/lib/libQtGui.so.4
#46 0xb8028456 in kdemain (argc=1, argv=0xbfd98094) at /build/buildd/kdebase-workspace-4.2.0/plasma/shells/desktop/main.cpp:54
#47 0x08048712 in main (argc=) at /build/buildd/kdebase-workspace-4.2.0/obj-i486-linux-gnu/plasma/shells/desktop/plasma_qgv_dummy.cpp:3

Please let me know what other info you need.