Application that crashed: dolphin
Version of the application: 1.2.80
KDE Version: 4.2.90 (KDE 4.2.90 (KDE 4.3 Beta2))
Qt Version: 4.5.0
Operating System: Linux 2.6.28-13-generic i686
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
It was a random crash.
I was just switching from one folder to another, and the file manager just crashed.
A file copy was running on the background.
The machine is not very new, and the disk has poor performance.

 -- Backtrace:
Application: Dolphin (dolphin), signal: Segmentation fault
[KCrash Handler]
#6  0xb7e3ecaf in KFileItem::determineMimeType () from /usr/lib/libkio.so.5
#7  0xb7e3ee0f in KFileItem::mimetype () from /usr/lib/libkio.so.5
#8  0xb7d15a55 in KFilePreviewGenerator::Private::createPreviews () from /usr/lib/libkfile.so.4
#9  0xb7d15e07 in KFilePreviewGenerator::Private::updateIcons () from /usr/lib/libkfile.so.4
#10 0xb7d15fc8 in KFilePreviewGenerator::Private::delayedIconUpdate () from /usr/lib/libkfile.so.4
#11 0xb7d16f0e in KFilePreviewGenerator::qt_metacall () from /usr/lib/libkfile.so.4
#12 0xb6747ca8 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#13 0xb6748932 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#14 0xb6783717 in QTimer::timeout () from /usr/lib/libQtCore.so.4
#15 0xb674d6fe in QTimer::timerEvent () from /usr/lib/libQtCore.so.4
#16 0xb674215f in QObject::event () from /usr/lib/libQtCore.so.4
#17 0xb6969e9c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#18 0xb697219e in QApplication::notify () from /usr/lib/libQtGui.so.4
#19 0xb76d5e8d in KApplication::notify () from /usr/lib/libkdeui.so.5
#20 0xb6731a3b in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#21 0xb6760d71 in ?? () from /usr/lib/libQtCore.so.4
#22 0xb675d4e0 in ?? () from /usr/lib/libQtCore.so.4
#23 0xb5ea7b88 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#24 0xb5eab0eb in ?? () from /usr/lib/libglib-2.0.so.0
#25 0xb5eab268 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#26 0xb675d438 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#27 0xb6a0b365 in ?? () from /usr/lib/libQtGui.so.4
#28 0xb673006a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#29 0xb67304aa in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#30 0xb6732959 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#31 0xb6969d17 in QApplication::exec () from /usr/lib/libQtGui.so.4
#32 0x0807a8af in _start ()

Reported using DrKonqi