Hey,
while the render process was on, I tried to hit the play button and got this. It does not crash when I press play when not rendering:

Application: Kdenlive (kdenlive), signal SIGSEGV

[Thread debugging using libthread_db enabled]

[New Thread 0xb563f720 (LWP 8815)]

[New Thread 0xaab06b90 (LWP 9062)]

[New Thread 0xb2718b90 (LWP 9057)]

[New Thread 0xb01fcb90 (LWP 8979)]

[KCrash handler]

#6 Render::sendSeekCommand (this=0x0, time=@0xbf94f628)

at /home/johannes/test/kdenlive-kde4/src/renderer.cpp:1012

#7 0x080c130c in Render::seek (this=0x0, time=@0xbf94f688)

at /home/johannes/test/kdenlive-kde4/src/renderer.cpp:189

#8 0x0810ce25 in CustomTrackView::setCursorPos (this=0x87fba70, pos=23,

seek=true)

at /home/johannes/test/kdenlive-kde4/src/customtrackview.cpp:1018

#9 0x080a979c in CustomRuler::mousePressEvent (this=0x876ae90,

event=0xbf94fbfc)

at /home/johannes/test/kdenlive-kde4/src/customruler.cpp:117

#10 0xb6aa8574 in QWidget::event () from /usr/lib/libQtGui.so.4

#11 0xb6d91d34 in QAbstractSlider::event () from /usr/lib/libQtGui.so.4

#12 0xb6a50c0c in QApplicationPrivate::notify_helper ()

from /usr/lib/libQtGui.so.4

#13 0xb6a55cc5 in QApplication::notify () from /usr/lib/libQtGui.so.4

#14 0xb7ce3603 in KApplication::notify () from /usr/lib/kde4/lib/libkdeui.so.5

#15 0xb74b06a9 in QCoreApplication::notifyInternal ()

from /usr/lib/libQtCore.so.4

#16 0xb6a52e11 in QApplicationPrivate::sendMouseEvent ()

from /usr/lib/libQtGui.so.4

#17 0xb6abccbd in ?? () from /usr/lib/libQtGui.so.4

#18 0xb6abb6a1 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4

#19 0xb6ae439a in ?? () from /usr/lib/libQtGui.so.4

#20 0xb5ae7bf8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0

#21 0xb5aeae5e in ?? () from /usr/lib/libglib-2.0.so.0

#22 0xb5aeb3ac in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0

#23 0xb74dbf98 in QEventDispatcherGlib::processEvents ()

from /usr/lib/libQtCore.so.4

#24 0xb6ae4195 in ?? () from /usr/lib/libQtGui.so.4

#25 0xb74af92d in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4

#26 0xb74afabd in QEventLoop::exec () from /usr/lib/libQtCore.so.4

#27 0xb74b1d3d in QCoreApplication::exec () from /usr/lib/libQtCore.so.4

#28 0xb6a50567 in QApplication::exec () from /usr/lib/libQtGui.so.4

#29 0x08093675 in main (argc=1, argv=0xbf950514)

at /home/johannes/test/kdenlive-kde4/src/main.cpp:72

#0 0xb7f91410 in __kernel_vsyscall ()



--
Johannes Wilm
http://www.johanneswilm.org
tel: +5059173717