I installed the gnome-panel-dbgsym package, and got this backtrace when I set the preferences on the gnome-panel to show windows from all workspaces. Based on further observation, it seems that the issue has to do with something bad happening when notifications are sent to the gnome-panel by apps. I have attached the stack traces, there doesn't seem to be any more info though. Sample output of top: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 13529 vijayr 16 0 73384 46m 10m R 64 2.3 0:32.17 gnome-panel 5312 root 15 0 424m 76m 8192 R 22 3.8 8:49.97 Xorg Debug stack traces shakti:~$ gdb `which gnome-panel` 13529 GNU gdb 6.6-debian Copyright (C) 2006 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i486-linux-gnu"... Using host libthread_db library "/lib/tls/i686/cmov/libthread_db.so.1". Attaching to program: /usr/bin/gnome-panel, process 13529 Reading symbols from /usr/lib/libgnome-desktop-2.so.2...done. Loaded symbols for /usr/lib/libgnome-desktop-2.so.2 Reading symbols from /usr/lib/libgnomeui-2.so.0...done. Loaded symbols for /usr/lib/libgnomeui-2.so.0 Reading symbols from /usr/lib/libbonoboui-2.so.0...done. Loaded symbols for /usr/lib/libbonoboui-2.so.0 Reading symbols from /usr/lib/libgnomecanvas-2.so.0...done. Loaded symbols for /usr/lib/libgnomecanvas-2.so.0 Reading symbols from /usr/lib/libgnome-2.so.0...done. Loaded symbols for /usr/lib/libgnome-2.so.0 Reading symbols from /usr/lib/libbonobo-2.so.0...done. Loaded symbols for /usr/lib/libbonobo-2.so.0 Reading symbols from /usr/lib/libbonobo-activation.so.4...done. Loaded symbols for /usr/lib/libbonobo-activation.so.4 Reading symbols from /usr/lib/libart_lgpl_2.so.2...done. Loaded symbols for /usr/lib/libart_lgpl_2.so.2 Reading symbols from /usr/lib/libgnomevfs-2.so.0...done. Loaded symbols for /usr/lib/libgnomevfs-2.so.0 Reading symbols from /usr/lib/libglade-2.0.so.0...done. Loaded symbols for /usr/lib/libglade-2.0.so.0 Reading symbols from /usr/lib/libgtk-x11-2.0.so.0...done. Loaded symbols for /usr/lib/libgtk-x11-2.0.so.0 Reading symbols from /usr/lib/libgdk-x11-2.0.so.0...done. Loaded symbols for /usr/lib/libgdk-x11-2.0.so.0 Reading symbols from /usr/lib/libatk-1.0.so.0...done. Loaded symbols for /usr/lib/libatk-1.0.so.0 Reading symbols from /usr/lib/libgdk_pixbuf-2.0.so.0...done. Loaded symbols for /usr/lib/libgdk_pixbuf-2.0.so.0 Reading symbols from /usr/lib/libpango-1.0.so.0...done. Loaded symbols for /usr/lib/libpango-1.0.so.0 Reading symbols from /usr/lib/libcairo.so.2...done. Loaded symbols for /usr/lib/libcairo.so.2 Reading symbols from /usr/lib/libgconf-2.so.4...done. Loaded symbols for /usr/lib/libgconf-2.so.4 Reading symbols from /usr/lib/libORBit-2.so.0...done. Loaded symbols for /usr/lib/libORBit-2.so.0 Reading symbols from /usr/lib/libgnome-menu.so.2...done. Loaded symbols for /usr/lib/libgnome-menu.so.2 Reading symbols from /usr/lib/libdbus-glib-1.so.2...done. Loaded symbols for /usr/lib/libdbus-glib-1.so.2 Reading symbols from /usr/lib/libgobject-2.0.so.0...done. Loaded symbols for /usr/lib/libgobject-2.0.so.0 Reading symbols from /usr/lib/libglib-2.0.so.0...done. Loaded symbols for /usr/lib/libglib-2.0.so.0 Reading symbols from /usr/lib/libXau.so.6...done. Loaded symbols for /usr/lib/libXau.so.6 Reading symbols from /usr/lib/libX11.so.6...done. Loaded symbols for /usr/lib/libX11.so.6 Reading symbols from /lib/tls/i686/cmov/libm.so.6...done. Loaded symbols for /lib/tls/i686/cmov/libm.so.6 Reading symbols from /lib/tls/i686/cmov/libpthread.so.0...done. [Thread debugging using libthread_db enabled] [New Thread -1226201424 (LWP 13529)] Loaded symbols for /lib/tls/i686/cmov/libpthread.so.0 Reading symbols from /lib/tls/i686/cmov/libc.so.6...done. Loaded symbols for /lib/tls/i686/cmov/libc.so.6 Reading symbols from /usr/lib/libxml2.so.2...done. Loaded symbols for /usr/lib/libxml2.so.2 Reading symbols from /usr/lib/libSM.so.6...done. Loaded symbols for /usr/lib/libSM.so.6 Reading symbols from /usr/lib/libICE.so.6...done. Loaded symbols for /usr/lib/libICE.so.6 Reading symbols from /lib/libpopt.so.0...done. Loaded symbols for /lib/libpopt.so.0 Reading symbols from /usr/lib/libpangocairo-1.0.so.0...done. Loaded symbols for /usr/lib/libpangocairo-1.0.so.0 Reading symbols from /usr/lib/libfontconfig.so.1...done. Loaded symbols for /usr/lib/libfontconfig.so.1 Reading symbols from /usr/lib/libXext.so.6...done. Loaded symbols for /usr/lib/libXext.so.6 Reading symbols from /usr/lib/libXrender.so.1...done. Loaded symbols for /usr/lib/libXrender.so.1 Reading symbols from /usr/lib/libXinerama.so.1...done. Loaded symbols for /usr/lib/libXinerama.so.1 Reading symbols from /usr/lib/libXi.so.6...done. Loaded symbols for /usr/lib/libXi.so.6 Reading symbols from /usr/lib/libXrandr.so.2...done. Loaded symbols for /usr/lib/libXrandr.so.2 Reading symbols from /usr/lib/libXcursor.so.1...done. Loaded symbols for /usr/lib/libXcursor.so.1 Reading symbols from /usr/lib/libXcomposite.so.1...done. Loaded symbols for /usr/lib/libXcomposite.so.1 Reading symbols from /usr/lib/libXdamage.so.1...done. Loaded symbols for /usr/lib/libXdamage.so.1 Reading symbols from /usr/lib/libXfixes.so.3...done. Loaded symbols for /usr/lib/libXfixes.so.3 Reading symbols from /usr/lib/libgmodule-2.0.so.0...done. Loaded symbols for /usr/lib/libgmodule-2.0.so.0 Reading symbols from /lib/tls/i686/cmov/libdl.so.2...done. Loaded symbols for /lib/tls/i686/cmov/libdl.so.2 Reading symbols from /usr/lib/libgthread-2.0.so.0...done. Loaded symbols for /usr/lib/libgthread-2.0.so.0 Reading symbols from /lib/tls/i686/cmov/librt.so.1...done. Loaded symbols for /lib/tls/i686/cmov/librt.so.1 Reading symbols from /usr/lib/libstartup-notification-1.so.0...done. Loaded symbols for /usr/lib/libstartup-notification-1.so.0 Reading symbols from /usr/lib/libgnome-keyring.so.0...done. Loaded symbols for /usr/lib/libgnome-keyring.so.0 Reading symbols from /usr/lib/libjpeg.so.62...done. Loaded symbols for /usr/lib/libjpeg.so.62 Reading symbols from /usr/lib/libgailutil.so.18...done. Loaded symbols for /usr/lib/libgailutil.so.18 Reading symbols from /usr/lib/libpangoft2-1.0.so.0...done. Loaded symbols for /usr/lib/libpangoft2-1.0.so.0 Reading symbols from /usr/lib/libesd.so.0...done. Loaded symbols for /usr/lib/libesd.so.0 Reading symbols from /usr/lib/libaudiofile.so.0...done. Loaded symbols for /usr/lib/libaudiofile.so.0 Reading symbols from /usr/lib/libORBitCosNaming-2.so.0...done. Loaded symbols for /usr/lib/libORBitCosNaming-2.so.0 Reading symbols from /usr/lib/libdbus-1.so.3...done. Loaded symbols for /usr/lib/libdbus-1.so.3 Reading symbols from /usr/lib/libgnutls.so.13...done. Loaded symbols for /usr/lib/libgnutls.so.13 Reading symbols from /usr/lib/libavahi-glib.so.1...done. Loaded symbols for /usr/lib/libavahi-glib.so.1 Reading symbols from /usr/lib/libavahi-common.so.3...done. Loaded symbols for /usr/lib/libavahi-common.so.3 Reading symbols from /usr/lib/libavahi-client.so.3...done. Loaded symbols for /usr/lib/libavahi-client.so.3 Reading symbols from /lib/tls/i686/cmov/libresolv.so.2...done. Loaded symbols for /lib/tls/i686/cmov/libresolv.so.2 Reading symbols from /lib/libselinux.so.1...done. Loaded symbols for /lib/libselinux.so.1 Reading symbols from /lib/tls/i686/cmov/libutil.so.1...done. Loaded symbols for /lib/tls/i686/cmov/libutil.so.1 Reading symbols from /usr/lib/libfreetype.so.6...done. Loaded symbols for /usr/lib/libfreetype.so.6 Reading symbols from /usr/lib/libz.so.1...done. Loaded symbols for /usr/lib/libz.so.1 Reading symbols from /usr/lib/libpng12.so.0...done. Loaded symbols for /usr/lib/libpng12.so.0 Reading symbols from /lib/tls/i686/cmov/libnsl.so.1...done. Loaded symbols for /lib/tls/i686/cmov/libnsl.so.1 Reading symbols from /usr/lib/libXdmcp.so.6...done. Loaded symbols for /usr/lib/libXdmcp.so.6 Reading symbols from /lib/ld-linux.so.2...done. Loaded symbols for /lib/ld-linux.so.2 Reading symbols from /usr/lib/libexpat.so.1...done. Loaded symbols for /usr/lib/libexpat.so.1 Reading symbols from /usr/lib/libasound.so.2...done. Loaded symbols for /usr/lib/libasound.so.2 Reading symbols from /usr/lib/libtasn1.so.3...done. Loaded symbols for /usr/lib/libtasn1.so.3 Reading symbols from /usr/lib/libgpg-error.so.0...done. Loaded symbols for /usr/lib/libgpg-error.so.0 Reading symbols from /usr/lib/libgcrypt.so.11...done. Loaded symbols for /usr/lib/libgcrypt.so.11 Reading symbols from /lib/libsepol.so.1...done. Loaded symbols for /lib/libsepol.so.1 Reading symbols from /lib/tls/i686/cmov/libnss_compat.so.2...done. Loaded symbols for /lib/tls/i686/cmov/libnss_compat.so.2 Reading symbols from /lib/tls/i686/cmov/libnss_nis.so.2...done. Loaded symbols for /lib/tls/i686/cmov/libnss_nis.so.2 Reading symbols from /lib/tls/i686/cmov/libnss_files.so.2...done. Loaded symbols for /lib/tls/i686/cmov/libnss_files.so.2 Reading symbols from /usr/lib/gconv/ISO8859-1.so...done. Loaded symbols for /usr/lib/gconv/ISO8859-1.so Reading symbols from /usr/lib/gtk-2.0/2.10.0/engines/libubuntulooks.so...done. Loaded symbols for /usr/lib/gtk-2.0/2.10.0/engines/libubuntulooks.so Reading symbols from /usr/lib/pango/1.6.0/modules/pango-basic-fc.so...done. Loaded symbols for /usr/lib/pango/1.6.0/modules/pango-basic-fc.so Reading symbols from /usr/lib/gtk-2.0/2.10.0/loaders/svg_loader.so...done. Loaded symbols for /usr/lib/gtk-2.0/2.10.0/loaders/svg_loader.so Reading symbols from /usr/lib/librsvg-2.so.2...done. Loaded symbols for /usr/lib/librsvg-2.so.2 Reading symbols from /usr/lib/libgsf-1.so.114...done. Loaded symbols for /usr/lib/libgsf-1.so.114 Reading symbols from /usr/lib/libcroco-0.6.so.3...done. Loaded symbols for /usr/lib/libcroco-0.6.so.3 Reading symbols from /lib/libbz2.so.1.0...done. Loaded symbols for /lib/libbz2.so.1.0 Reading symbols from /usr/lib/bonobo/monikers/libmoniker_std_2.so...done. Loaded symbols for /usr/lib/bonobo/monikers/libmoniker_std_2.so Reading symbols from /usr/lib/gnome-panel/libwnck-applet.so...Reading symbols from /usr/lib/debug/usr/lib/gnome-panel/libwnck-applet.so...done. done. Loaded symbols for /usr/lib/gnome-panel/libwnck-applet.so Reading symbols from /usr/lib/libpanel-applet-2.so.0...done. Loaded symbols for /usr/lib/libpanel-applet-2.so.0 Reading symbols from /usr/lib/liblpint-bonobo.so.0...done. Loaded symbols for /usr/lib/liblpint-bonobo.so.0 Reading symbols from /usr/lib/liblaunchpad-integration.so.0...done. Loaded symbols for /usr/lib/liblaunchpad-integration.so.0 Reading symbols from /usr/lib/libwnck-1.so.22...done. Loaded symbols for /usr/lib/libwnck-1.so.22 Reading symbols from /usr/lib/libXRes.so.1...done. Loaded symbols for /usr/lib/libXRes.so.1 Reading symbols from /usr/lib/gtk-2.0/2.10.0/loaders/libpixbufloader-png.so...done. Loaded symbols for /usr/lib/gtk-2.0/2.10.0/loaders/libpixbufloader-png.so 0xb721cccc in ?? () from /usr/lib/libpangoft2-1.0.so.0 (gdb) bt #0 0xb721cccc in ?? () from /usr/lib/libpangoft2-1.0.so.0 #1 0x084f7238 in ?? () #2 0xb778821c in ?? () from /usr/lib/libglib-2.0.so.0 #3 0xbfd00338 in ?? () #4 0xb75a4285 in pthread_getspecific () from /lib/tls/i686/cmov/libpthread.so.0 #5 0xb79085e0 in pango_font_map_load_fontset () from /usr/lib/libpango-1.0.so.0 #6 0xb79064c7 in ?? () from /usr/lib/libpango-1.0.so.0 #7 0x081164b8 in ?? () #8 0x08319ac0 in ?? () #9 0x08333b80 in ?? () #10 0x0814bed0 in ?? () #11 0xbfd00520 in ?? () #12 0xb792ce60 in ?? () from /usr/lib/libpango-1.0.so.0 #13 0xbfd004f8 in ?? () #14 0xbfd00520 in ?? () #15 0x08333b80 in ?? () #16 0x00000000 in ?? () (gdb) c Continuing. Program received signal SIGINT, Interrupt. [Switching to Thread -1226201424 (LWP 13529)] 0xffffe410 in __kernel_vsyscall () (gdb) bt #0 0xffffe410 in __kernel_vsyscall () #1 0xb75195ab in poll () from /lib/tls/i686/cmov/libc.so.6 #2 0xb7615839 in ?? () from /usr/lib/libX11.so.6 #3 0x080e17d8 in ?? () #4 0x00000001 in ?? () #5 0xffffffff in ?? () #6 0xb761e67f in _X11TransWrite () from /usr/lib/libX11.so.6 #7 0xb7615c2f in _XRead () from /usr/lib/libX11.so.6 #8 0xb7616604 in _XReply () from /usr/lib/libX11.so.6 #9 0xb76105da in XSync () from /usr/lib/libX11.so.6 #10 0xb5d6fa1a in ?? () from /usr/lib/libwnck-1.so.22 #11 0x080e1298 in ?? () #12 0x00000000 in ?? () (gdb) show threads Undefined show command: "threads". Try "help show". (gdb) info thread * 1 Thread -1226201424 (LWP 13529) 0xffffe410 in __kernel_vsyscall () (gdb) c Continuing. Program received signal SIGINT, Interrupt. 0xffffe410 in __kernel_vsyscall () (gdb) bt #0 0xffffe410 in __kernel_vsyscall () #1 0xb75195ab in poll () from /lib/tls/i686/cmov/libc.so.6 #2 0xb7615839 in ?? () from /usr/lib/libX11.so.6 #3 0x080e17d8 in ?? () #4 0x00000001 in ?? () #5 0xffffffff in ?? () #6 0xb761e67f in _X11TransWrite () from /usr/lib/libX11.so.6 #7 0xb7615c2f in _XRead () from /usr/lib/libX11.so.6 #8 0xb7616604 in _XReply () from /usr/lib/libX11.so.6 #9 0xb7611d04 in XTranslateCoordinates () from /usr/lib/libX11.so.6 #10 0xb79bc2db in gdk_window_get_origin () from /usr/lib/libgdk-x11-2.0.so.0 #11 0xb5d644e9 in ?? () from /usr/lib/libwnck-1.so.22 #12 0x08329468 in ?? () #13 0xbfd01b9c in ?? () #14 0xbfd01b98 in ?? () #15 0x0000000f in ?? () #16 0x0000001b in ?? () #17 0x00000000 in ?? ()