I can confirm identical behavior on my system as user or root. This is a clean install of 2009.2, all updates and then task-kde4-extra. Amarok running, open Dolphin select mp3 file, plays in Amarok, close Dolphin then crash screen pops up. Debugging provides;
Application: Dolphin (dolphin), signal: Segmentation fault
[KCrash Handler]
#9 0x0807ca71 in _start ()
#10 0x0807cf6a in _start ()
#11 0x0807dd71 in _start ()
#12 0x0807e624 in _start ()
#13 0xb65a3d46 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#14 0xb65a4a97 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#15 0xb65dffe1 in QTimer::timeout () from /usr/lib/libQtCore.so.4
#16 0xb65a96f6 in QTimer::timerEvent () from /usr/lib/libQtCore.so.4
#17 0xb659d903 in QObject::event () from /usr/lib/libQtCore.so.4
#18 0xb67917ec in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#19 0xb679930e in QApplication::notify () from /usr/lib/libQtGui.so.4
#20 0xb754d361 in KApplication::notify () from /usr/lib/libkdeui.so.5
#21 0xb658d43d in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#22 0xb65bc241 in QEventDispatcherUNIX::registerTimer () from /usr/lib/libQtCore.so.4
#23 0xb65b9a45 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#24 0xb5dca32c in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#25 0xb5dcdd68 in g_main_context_prepare () from /usr/lib/libglib-2.0.so.0
#26 0xb5dcde8e in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#27 0xb65b9731 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#28 0xb6834b1a in QX11Info::copyX11Data () from /usr/lib/libQtGui.so.4
#29 0xb658ba7d in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#30 0xb658bed1 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#31 0xb658e3aa in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#32 0xb6791664 in QApplication::exec () from /usr/lib/libQtGui.so.4
#33 0x08078f19 in _start ()
#34 0xb61a7a36 in __libc_start_main () from /lib/i686/libc.so.6
#35 0x08061e31 in _start ()
Strange one
Also, from command line Dolphin launch;
[root@localhost ~]# dolphin
Xlib: extension "Generic Event Extension" missing on display ":0.0".
Xlib: extension "Generic Event Extension" missing on display ":0.0".
Xlib: extension "Generic Event Extension" missing on display ":0.0".
Xlib: extension "Generic Event Extension" missing on display ":0.0".
[root@localhost ~]# "/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Invalid iterator."
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Invalid iterator."
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Invalid iterator."
socket(): Address family not supported by protocol
socket(): Address family not supported by protocol
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Invalid iterator."
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Unsupported operation (2)": "Invalid model"
"/usr/bin/dolphin(32386)" Error in thread 3044841168 : "Invalid iterator."
socket(): Address family not supported by protocol
QLayout: Attempting to add QLayout "" to PhononWidget "", which already has a layout
Xlib: extension "Generic Event Extension" missing on display ":0.0".
KCrash: Application 'dolphin' crashing...
sock_file=/root/.kde4/socket-localhost/kdeinit4__0