Version:            (using KDE Devel)
Installed from:    Compiled sources
Compiler:          cmake 2.4.7-1 
OS:                Linux

Here is the crash report. It happens consistently whenever visiting a page with embedded flash content, and can be avoided altogether if JavaScript is disabled (which blocks flash content to be displayed at all, but is far from an optimal solution).

Here is the backtrace:

Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1".
[Thread debugging using libthread_db enabled]
[New Thread -1238849856 (LWP 13036)]
[KCrash handler]
#6  0xffffe410 in __kernel_vsyscall ()
#7  0xb6634875 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb6636201 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb716901d in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb71690a1 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb71690f8 in qt_assert_x () from /usr/lib/libQtCore.so.4
#12 0xb12c3ad4 in NSPluginLoader::scanPlugins ()
   from /opt/kde4/lib/kde4/libnsplugin.so
#13 0xb12c3c4a in NSPluginLoader::NSPluginLoader ()
   from /opt/kde4/lib/kde4/libnsplugin.so
#14 0xb12c3d93 in NSPluginLoader::instance ()
   from /opt/kde4/lib/kde4/libnsplugin.so
#15 0xb12bc618 in PluginFactory::PluginFactory ()
   from /opt/kde4/lib/kde4/libnsplugin.so
#16 0xb12bc766 in qt_plugin_instance () from /opt/kde4/lib/kde4/libnsplugin.so
#17 0xb721191c in QPluginLoader::instance () from /usr/lib/libQtCore.so.4
#18 0xb7b1b285 in KPluginLoader::factory () from /opt/kde4/lib/libkdecore.so.5
#19 0xb42d0c41 in KHTMLPart::createPart () from /opt/kde4/lib/libkhtml.so.5
#20 0xb42af5d8 in KHTMLPart::processObjectRequest ()
   from /opt/kde4/lib/libkhtml.so.5
#21 0xb42b2a54 in KHTMLPart::requestObject () from /opt/kde4/lib/libkhtml.so.5
#22 0xb42b3cc4 in KHTMLPart::requestObject () from /opt/kde4/lib/libkhtml.so.5
#23 0xb441f52a in khtml::RenderPartObject::updateWidget ()
   from /opt/kde4/lib/libkhtml.so.5
#24 0xb441aa1e in khtml::RenderPartObject::close ()
   from /opt/kde4/lib/libkhtml.so.5
#25 0xb432909c in DOM::NodeImpl::attach () from /opt/kde4/lib/libkhtml.so.5
#26 0xb4329a8c in DOM::NodeBaseImpl::attach ()
   from /opt/kde4/lib/libkhtml.so.5
#27 0xb4392046 in DOM::HTMLObjectBaseElementImpl::attach ()
   from /opt/kde4/lib/libkhtml.so.5
#28 0xb43925fb in DOM::HTMLEmbedElementImpl::attach ()
   from /opt/kde4/lib/libkhtml.so.5
#29 0xb432da1e in DOM::NodeBaseImpl::appendChild ()
   from /opt/kde4/lib/libkhtml.so.5
#30 0xb43677b5 in DOM::HTMLElementImpl::setInnerHTML ()
   from /opt/kde4/lib/libkhtml.so.5
#31 0xb44b27b5 in KJS::HTMLElement::putValueProperty ()
   from /opt/kde4/lib/libkhtml.so.5
#32 0xb44b3a07 in KJS::HTMLElement::put () from /opt/kde4/lib/libkhtml.so.5
#33 0xb472bf21 in KJS::AssignDotNode::evaluate ()
   from /opt/kde4/lib/libkjs.so.4
#34 0xb4720bd4 in KJS::ExprStatementNode::execute ()
   from /opt/kde4/lib/libkjs.so.4
#35 0xb4720f97 in KJS::SourceElementsNode::execute ()
   from /opt/kde4/lib/libkjs.so.4
#36 0xb4720a44 in KJS::BlockNode::execute () from /opt/kde4/lib/libkjs.so.4
#37 0xb47233a0 in KJS::IfNode::execute () from /opt/kde4/lib/libkjs.so.4
#38 0xb4720f97 in KJS::SourceElementsNode::execute ()
   from /opt/kde4/lib/libkjs.so.4
#39 0xb4720a44 in KJS::BlockNode::execute () from /opt/kde4/lib/libkjs.so.4
#40 0xb475db07 in KJS::DeclaredFunctionImp::execute ()
   from /opt/kde4/lib/libkjs.so.4
#41 0xb475e1fc in KJS::FunctionImp::callAsFunction ()
   from /opt/kde4/lib/libkjs.so.4
#42 0xb47649bc in KJS::JSObject::call () from /opt/kde4/lib/libkjs.so.4
#43 0xb4726c45 in KJS::FunctionCallDotNode::evaluate ()
   from /opt/kde4/lib/libkjs.so.4
#44 0xb4720bd4 in KJS::ExprStatementNode::execute ()
   from /opt/kde4/lib/libkjs.so.4
#45 0xb4720f97 in KJS::SourceElementsNode::execute ()
   from /opt/kde4/lib/libkjs.so.4
#46 0xb4720a44 in KJS::BlockNode::execute () from /opt/kde4/lib/libkjs.so.4
#47 0xb4767c74 in KJS::Interpreter::evaluate () from /opt/kde4/lib/libkjs.so.4
#48 0xb4767d56 in KJS::Interpreter::evaluate () from /opt/kde4/lib/libkjs.so.4
#49 0xb44ec146 in KJS::KJSProxyImpl::evaluate ()
   from /opt/kde4/lib/libkhtml.so.5
#50 0xb42c31ff in KHTMLPart::executeScript () from /opt/kde4/lib/libkhtml.so.5
#51 0xb4352779 in khtml::HTMLTokenizer::scriptExecution ()
   from /opt/kde4/lib/libkhtml.so.5
#52 0xb43545de in khtml::HTMLTokenizer::scriptHandler ()
   from /opt/kde4/lib/libkhtml.so.5
#53 0xb4356b7f in khtml::HTMLTokenizer::parseSpecial ()
   from /opt/kde4/lib/libkhtml.so.5
#54 0xb4358940 in khtml::HTMLTokenizer::parseTag ()
   from /opt/kde4/lib/libkhtml.so.5
#55 0xb435a90b in khtml::HTMLTokenizer::write ()
   from /opt/kde4/lib/libkhtml.so.5
#56 0xb435bd37 in khtml::HTMLTokenizer::notifyFinished ()
   from /opt/kde4/lib/libkhtml.so.5
#57 0xb4473014 in khtml::CachedScript::checkNotify ()
   from /opt/kde4/lib/libkhtml.so.5
#58 0xb4473ebb in khtml::CachedScript::data ()
   from /opt/kde4/lib/libkhtml.so.5
#59 0xb44735d5 in khtml::Loader::slotFinished ()
   from /opt/kde4/lib/libkhtml.so.5
#60 0xb447a101 in khtml::Loader::qt_metacall ()
   from /opt/kde4/lib/libkhtml.so.5
#61 0xb7238c04 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#62 0xb7239079 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#63 0xb7a0d7e3 in KJob::result () from /opt/kde4/lib/libkdecore.so.5
#64 0xb7a0db62 in KJob::emitResult () from /opt/kde4/lib/libkdecore.so.5
#65 0xb7c0b773 in KIO::SimpleJob::slotFinished ()
   from /opt/kde4/lib/libkio.so.5
#66 0xb7c110df in KIO::TransferJob::slotFinished ()
   from /opt/kde4/lib/libkio.so.5
#67 0xb7c146ea in KIO::TransferJob::qt_metacall ()
   from /opt/kde4/lib/libkio.so.5
#68 0xb7238c04 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#69 0xb7239079 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#70 0xb7cdc517 in KIO::SlaveInterface::finished ()
   from /opt/kde4/lib/libkio.so.5
#71 0xb7ce08bf in KIO::SlaveInterface::dispatch ()
   from /opt/kde4/lib/libkio.so.5
#72 0xb7cdcccd in KIO::SlaveInterface::dispatch ()
   from /opt/kde4/lib/libkio.so.5
#73 0xb7cceccd in KIO::Slave::gotInput () from /opt/kde4/lib/libkio.so.5
#74 0xb7ccfa3d in KIO::Slave::qt_metacall () from /opt/kde4/lib/libkio.so.5
#75 0xb7238c04 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#76 0xb7239079 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#77 0xb7bd7d17 in KIO::Connection::readyRead () from /opt/kde4/lib/libkio.so.5
#78 0xb7bd9b90 in KIO::ConnectionPrivate::dequeue ()
   from /opt/kde4/lib/libkio.so.5
#79 0xb7bd9c25 in KIO::Connection::qt_metacall ()
   from /opt/kde4/lib/libkio.so.5
#80 0xb72345c4 in QMetaCallEvent::placeMetaCall ()
   from /usr/lib/libQtCore.so.4
#81 0xb7239933 in QObject::event () from /usr/lib/libQtCore.so.4
#82 0xb6a0344d in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#83 0xb6a0374e in QApplication::notify () from /usr/lib/libQtGui.so.4
#84 0xb77c383a in KApplication::notify () from /opt/kde4/lib/libkdeui.so.5
#85 0xb7227456 in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#86 0xb722a81f in ?? () from /usr/lib/libQtCore.so.4
#87 0xbf93f9ac in ?? ()
#88 0x08471378 in ?? ()
#89 0x08d91978 in ?? ()
#90 0xb716d3d7 in ?? () from /usr/lib/libQtCore.so.4
#91 0x0804bf74 in ?? ()
#92 0xb72ace20 in ?? () from /usr/lib/libQtCore.so.4
#93 0xbf93f598 in ?? ()
#94 0xb722792d in QCoreApplicationPrivate::sendPostedEvents ()
   from /usr/lib/libQtCore.so.4
Backtrace stopped: frame did not save the PC
#0  0xffffe410 in __kernel_vsyscall ()