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 2.6.31-19-generic i686
Distribution: Ubuntu 9.10

What I was doing when the application crashed:
After login to the system I get an error message, that Plasma has been crashed, and bug reporting wizard is showing. 
When my system worked properly I added some plasma widgets to the desktop and played with desktop effects. Now after login plasma is crashing all the time.
All other applications are working (I use Alt+F2 to run them), but there are no K-Menu, desktop panels and widgets.

 -- Backtrace:
Application: Plasma Workspace (kdeinit4), signal: Segmentation fault
[Current thread is 1 (Thread 0xb770a700 (LWP 5504))]

Thread 2 (Thread 0xab08ab70 (LWP 5507)):
#0  0x00600422 in __kernel_vsyscall ()
#1  0x00259e15 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib/tls/i686/cmov/libpthread.so.0
#2  0x00b7487d in pthread_cond_wait () from /lib/tls/i686/cmov/libc.so.6
#3  0x0066fe67 in QWaitConditionPrivate::wait (this=0x95c86d0, mutex=0x95c86cc, time=4294967295) at thread/qwaitcondition_unix.cpp:87
#4  QWaitCondition::wait (this=0x95c86d0, mutex=0x95c86cc, time=4294967295) at thread/qwaitcondition_unix.cpp:159
#5  0x008cd922 in QHostInfoAgent::run (this=0x95c86c0) at kernel/qhostinfo.cpp:260
#6  0x0066ee32 in QThreadPrivate::start (arg=0x95c86c0) at thread/qthread_unix.cpp:188
#7  0x0025580e in start_thread () from /lib/tls/i686/cmov/libpthread.so.0
#8  0x00b678de in clone () from /lib/tls/i686/cmov/libc.so.6

Thread 1 (Thread 0xb770a700 (LWP 5504)):
[KCrash Handler]
#6  0x062596ee in Plasma::Applet::flushPendingConstraintsEvents (this=0x95d8dc0) at ../../plasma/applet.cpp:1109
#7  0x0627d7dd in Plasma::Corona::loadLayout (this=0x8d4ec08, configName=...) at ../../plasma/corona.cpp:379
#8  0x0627e8be in Plasma::Corona::initializeLayout (this=0x8d4ec08, configName=...) at ../../plasma/corona.cpp:324
#9  0x014221d6 in PlasmaApp::corona (this=0x8c473d0) at ../../../../plasma/shells/desktop/plasmaapp.cpp:574
#10 0x014224da in PlasmaApp::setupDesktop (this=0x8c473d0) at ../../../../plasma/shells/desktop/plasmaapp.cpp:252
#11 0x01422733 in PlasmaApp::qt_metacall (this=0x8c473d0, _c=QMetaObject::InvokeMetaMethod, _id=30, _a=0xbf970e2c) at ./plasmaapp.moc:115
#12 0x00775263 in QMetaObject::activate (sender=0x8d416e0, from_signal_index=4, to_signal_index=4, argv=0x0) at kernel/qobject.cpp:3113
#13 0x00775ec2 in QMetaObject::activate (sender=0x8d416e0, m=0x84f908, local_signal_index=0, argv=0x0) at kernel/qobject.cpp:3187
#14 0x0077a387 in QSingleShotTimer::timeout (this=0x8d416e0) at .moc/release-shared/qtimer.moc:76
#15 0x0077a49c in QSingleShotTimer::timerEvent (this=0x8d416e0) at kernel/qtimer.cpp:298
#16 0x0076f3bf in QObject::event (this=0x8d416e0, e=0xbf9712c0) at kernel/qobject.cpp:1075
#17 0x02474f54 in QApplicationPrivate::notify_helper (this=0x8c6e218, receiver=0x8d416e0, e=0xbf9712c0) at kernel/qapplication.cpp:4056
#18 0x0247c67c in QApplication::notify (this=0x8c473d0, receiver=0x8d416e0, e=0xbf9712c0) at kernel/qapplication.cpp:3603
#19 0x01180bfa in KApplication::notify (this=0x8c473d0, receiver=0x8d416e0, event=0xbf9712c0) at ../../kdeui/kernel/kapplication.cpp:302
#20 0x0075f6cb in QCoreApplication::notifyInternal (this=0x8c473d0, receiver=0x8d416e0, event=0xbf9712c0) at kernel/qcoreapplication.cpp:610
#21 0x0078c7ce in QCoreApplication::sendEvent (this=0x8c70e34) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:213
#22 QTimerInfoList::activateTimers (this=0x8c70e34) at kernel/qeventdispatcher_unix.cpp:572
#23 0x0078a0e0 in timerSourceDispatch (source=0x8c70e00) at kernel/qeventdispatcher_glib.cpp:165
#24 0x00531e88 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#25 0x00535730 in ?? () from /lib/libglib-2.0.so.0
#26 0x00535863 in g_main_context_iteration () from /lib/libglib-2.0.so.0
#27 0x0078a02c in QEventDispatcherGlib::processEvents (this=0x8c6e008, flags=...) at kernel/qeventdispatcher_glib.cpp:327
#28 0x02515be5 in QGuiEventDispatcherGlib::processEvents (this=0x8c6e008, flags=...) at kernel/qguieventdispatcher_glib.cpp:202
#29 0x0075dc79 in QEventLoop::processEvents (this=0xbf971584, flags=) at kernel/qeventloop.cpp:149
#30 0x0075e0ca in QEventLoop::exec (this=0xbf971584, flags=...) at kernel/qeventloop.cpp:201
#31 0x0076053f in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#32 0x02474dd7 in QApplication::exec () at kernel/qapplication.cpp:3525
#33 0x0140580d in kdemain (argc=1, argv=0x8c27c88) at ../../../../plasma/shells/desktop/main.cpp:50
#34 0x0804dde1 in launch (argc=<value optimized out>, _name=<value optimized out>, args=<value optimized out>, cwd=0x0, envc=0, envs=0x8bf9440 "", reset_env=false, tty=0x0, avoid_loops=false, 
    startup_id_str=0x80511a5 "0") at ../../kinit/kinit.cpp:677
#35 0x0804ea35 in handle_launcher_request (sock=<value optimized out>, who=<value optimized out>) at ../../kinit/kinit.cpp:1169
#36 0x0804eeac in handle_requests (waitForPid=<value optimized out>) at ../../kinit/kinit.cpp:1362
#37 0x0804fbaf in main (argc=2, argv=0xbf971de4, envp=0xbf971df0) at ../../kinit/kinit.cpp:1793

Reported using DrKonqi