When using swfdec with flashblock, Firefox crashes when clicking on the flashblock button (not always, but in most cases).

I'm using the git versions of swfdec and swfdec-mozilla with Firefox 3.0 beta 5 as shipped by Fedora 9.  Flashblock is vesrion 1.5.6a (unstable).  It can be downloaded from http://flashblock.mozdev.org/

"firefox -g" gives following backtrace:

about:blank is either a broken URL or Swfdec can't parse it

Program received signal SIGSEGV, Segmentation fault.
0x00000031b100d584 in IA__g_object_unref (_object=<value optimized out>) at gobject.c:1742
1742      g_return_if_fail (G_IS_OBJECT (object));
Missing separate debuginfos, use: debuginfo-install a52dec.x86_64 faac.x86_64 faad2.x86_64 ffmpeg.x86_64 gsm.x86_64 gstreamer-ffmpeg.x86_64 gstreamer-plugins-ugly.x86_64 keyutils.x86_64 lame.x86_64 libid3tag.x86_64 libmad.x86_64 libmp4v2.x86_64 libvorbis.x86_64 x264.x86_64 xvidcore.x86_64
(gdb) where
#0  0x00000031b100d584 in IA__g_object_unref (_object=<value optimized out>) at gobject.c:1742
#1  0x00007fe755655aac in swfmoz_player_dispose (object=0x7fe751044640) at swfmoz_player.c:440
#2  0x00000031b100d632 in IA__g_object_unref (_object=<value optimized out>) at gobject.c:1765
#3  0x00007fe75565154a in plugin_destroy (instance=0x7fe752657fc0, save=<value optimized out>)
    at plugin.c:311
#4  0x00000031c42898ac in ns4xPluginInstance::Stop (this=<value optimized out>)
    at ns4xPluginInstance.cpp:955
#5  0x00000031c3ded0d5 in DoStopPlugin (aInstanceOwner=<value optimized out>, 
    aDelayedStop=<value optimized out>) at nsObjectFrame.cpp:1776
#6  0x00000031c3ded193 in nsObjectFrame::StopPluginInternal (this=<value optimized out>, 
    aDelayedStop=<value optimized out>) at nsObjectFrame.cpp:1916
#7  0x00000031c3ded1fb in nsObjectFrame::PrepareInstanceOwner (this=<value optimized out>)
    at nsObjectFrame.cpp:1606
#8  0x00000031c3dedb6b in nsObjectFrame::Instantiate (this=<value optimized out>, 
    aMimeType=<value optimized out>, aURI=<value optimized out>) at nsObjectFrame.cpp:1670
#9  0x00000031c3efd29b in nsObjectLoadingContent::Instantiate (this=<value optimized out>, 
    aFrame=<value optimized out>, aMIMEType=<value optimized out>, aURI=<value optimized out>)
    at nsObjectLoadingContent.cpp:1681
#10 0x00000031c3efffd0 in nsAsyncInstantiateEvent::Run (this=<value optimized out>)
    at nsObjectLoadingContent.cpp:147
#11 0x00000031c4416a9e in nsThread::ProcessNextEvent (this=<value optimized out>, 
    mayWait=<value optimized out>, result=<value optimized out>) at nsThread.cpp:510
#12 0x00000031c43e82f6 in NS_ProcessNextEvent_P (thread=<value optimized out>, 
    mayWait=<value optimized out>) at nsThreadUtils.cpp:227
#13 0x00000031c436010d in nsBaseAppShell::Run (this=<value optimized out>)
    at nsBaseAppShell.cpp:170
#14 0x00000031c42235bd in nsAppStartup::Run (this=<value optimized out>)
    at nsAppStartup.cpp:181
#15 0x00000031c3c1f73b in XRE_main (argc=<value optimized out>, argv=<value optimized out>, 
---Type <return> to continue, or q <return> to quit---
    aAppData=<value optimized out>) at nsAppRunner.cpp:3154
#16 0x0000000000401665 in __gxx_personality_v0 ()
    at ../../../../libstdc++-v3/libsupc++/eh_personality.cc:363
#17 0x00000031aa81e32a in __libc_start_main (main=<value optimized out>, 
    argc=<value optimized out>, ubp_av=<value optimized out>, init=<value optimized out>, 
    fini=<value optimized out>, rtld_fini=<value optimized out>, stack_end=Could not find the frame base for "__libc_start_main".
)
    at libc-start.c:220
#18 0x0000000000401159 in __gxx_personality_v0 ()
    at ../../../../libstdc++-v3/libsupc++/eh_personality.cc:363
#19 0x00007fff611881f8 in ?? ()
#20 0x000000000000001c in ?? ()
#21 0x0000000000000001 in ?? ()
#22 0x00007fff61189394 in ?? ()
#23 0x0000000000000000 in ?? ()
(gdb)