Version:            (using KDE KDE 3.5.6)
Installed from:    Ubuntu Packages
OS:                Linux

Very hard to reproduce the crash, but I will include the backtrace that I got this last time. I started to use Kubuntu instead of Ubuntu because I would get similar crashes in Firefox and Swiftfox, but the crashes seem to be following me. It's possible that Gmail may be involved after reading a previous bug report however, as I usually have it open. 

Backtrace below:

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Using host libthread_db library "/lib/libthread_db.so.1".
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[Thread debugging using libthread_db enabled]
[New Thread 47626408411152 (LWP 5752)]
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[KCrash handler]
#5  0x00002b50de0a1a02 in QShared::ref () from /usr/lib/libqt-mt.so.3
#6  0x00002b50de473209 in QString::QString () from /usr/lib/libqt-mt.so.3
#7  0x00002b50df279bf1 in KXMLGUIClient::xmlFile ()
   from /usr/lib/libkdeui.so.4
#8  0x00002b50df349405 in KToolBar::applyAppearanceSettings ()
   from /usr/lib/libkdeui.so.4
#9  0x00002b50df349aa6 in KToolBar::applySettings ()
   from /usr/lib/libkdeui.so.4
#10 0x00002b50df35aa9b in KMainWindow::applyMainWindowSettings ()
   from /usr/lib/libkdeui.so.4
#11 0x00002b50dc58c867 in KParts::MainWindow::createGUI ()
   from /usr/lib/libkparts.so.2
#12 0x00002b50e3d79049 in KonqMainWindow::slotPartActivated ()
   from /usr/lib/libkdeinit_konqueror.so
#13 0x00002b50e3d97d4b in KonqViewManager::qt_invoke ()
   from /usr/lib/libkdeinit_konqueror.so
#14 0x00002b50de174ce2 in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#15 0x00002b50de17587c in QObject::activate_signal ()
   from /usr/lib/libqt-mt.so.3
#16 0x00002b50de4e4a1a in QTimer::timeout () from /usr/lib/libqt-mt.so.3
#17 0x00002b50de19b1a3 in QTimer::event () from /usr/lib/libqt-mt.so.3
#18 0x00002b50de1101d6 in QApplication::internalNotify ()
   from /usr/lib/libqt-mt.so.3
#19 0x00002b50de111f65 in QApplication::notify () from /usr/lib/libqt-mt.so.3
#20 0x00002b50dda5f7a8 in KApplication::notify ()
   from /usr/lib/libkdecore.so.4
#21 0x00002b50de0a2cc2 in QApplication::sendEvent ()
   from /usr/lib/libqt-mt.so.3
#22 0x00002b50de103490 in QEventLoop::activateTimers ()
   from /usr/lib/libqt-mt.so.3
#23 0x00002b50de0b73ef in QEventLoop::processEvents ()
   from /usr/lib/libqt-mt.so.3
#24 0x00002b50de12970b in QEventLoop::enterLoop () from /usr/lib/libqt-mt.so.3
#25 0x00002b50de129513 in QEventLoop::exec () from /usr/lib/libqt-mt.so.3
#26 0x00002b50de111c9c in QApplication::exec () from /usr/lib/libqt-mt.so.3
#27 0x00002b50e3d94c5c in kdemain () from /usr/lib/libkdeinit_konqueror.so
#28 0x0000000000407851 in ?? ()
#29 0x000000000040818c in ?? ()
#30 0x0000000000408535 in ?? ()
#31 0x00000000004095fa in ?? ()
#32 0x00002b50dcf568e4 in __libc_start_main () from /lib/libc.so.6
#33 0x0000000000404df9 in ?? ()
#34 0x00007fffce77c2a8 in ?? ()
#35 0x0000000000000000 in ?? ()