Version:            (using KDE 4.3.0)
Compiler:          gcc-Version 4.3.4 (Gentoo 4.3.4 p1.0, pie-10.1.5) CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"
OS:                Linux
Installed from:    Gentoo Packages

When running firefox 3.5 under KDE 4.x the firefox process is not terminated after the browser is closed. After I close firefox and try to re-open it afterwards, firefox refuses to start because of an already running instance. Only if I kill the firefox process by hand I can re-open the browser. It seems that this problem occures _only_ with kde 4.x, when using i.e. fluxbox or kde 3.5.x the problem does not occure.

Even after flushing all my settings and creating a new profile the problem persists. Starting firefox in safe mode with all extensions disabled does not help.

(see also http://forums.gentoo.org/viewtopic-t-787903-highlight-firefox+process.html)

I use: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.2) Gecko/20090813 Gentoo Firefox/3.5.2

emerge --info:
-----------------
Portage 2.1.6.13 (default/linux/amd64/10.0/desktop, gcc-4.3.4, glibc-2.10.1-r0, 2.6.30-gentoo-r1 x86_64)
=================================================================
System uname: Linux-2.6.30-gentoo-r1-x86_64-Intel-R-_Pentium-R-_D_CPU_3.00GHz-with-gentoo-2.0.1
Timestamp of tree: Fri, 14 Aug 2009 20:00:20 +0000
ccache version 2.4 [enabled]
app-shells/bash:     4.0_p28
dev-java/java-config: 2.1.8-r1
dev-lang/python:     2.5.4-r2, 2.6.2-r1, 3.1
dev-python/pycrypto: 2.0.1-r8
dev-util/ccache:     2.4-r8
dev-util/cmake:      2.6.4-r2
sys-apps/baselayout: 2.0.1
sys-apps/openrc:     0.4.3-r3
sys-apps/sandbox:    2.0
sys-devel/autoconf:  2.13, 2.63-r1
sys-devel/automake:  1.5, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2, 1.10.2, 1.11
sys-devel/binutils:  2.19.1-r1
sys-devel/gcc-config: 1.4.1
sys-devel/libtool:   2.2.6a
virtual/os-headers:  2.6.30-r1
ACCEPT_KEYWORDS="amd64 ~amd64"
CBUILD="x86_64-pc-linux-gnu"
CFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"
CHOST="x86_64-pc-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/3.5/env /usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/share/config /var/lib/hsqldb"
CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/env.d /etc/env.d/java/ /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/php/apache2-php5/ext-active/ /etc/php/cgi-php5/ext-active/ /etc/php/cli-php5/ext-active/ /etc/revdep-rebuild /etc/sandbox.d /etc/splash /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c /etc/udev/rules.d"
CXXFLAGS="-march=native -O2 -pipe -fomit-frame-pointer"
DISTDIR="/media/linux_data/portage-distfiles"
EMERGE_DEFAULT_OPTS="--quiet"
FEATURES="ccache distlocks fixpackages metadata-transfer parallel-fetch patchtree protect-owned sandbox sfperms strict unmerge-orphans userfetch"
GENTOO_MIRRORS="ftp://ftp.uni-erlangen.de/pub/mirrors/gentoo"
LANG="de_DE.utf8"
LC_ALL="de_DE.utf8"
LDFLAGS="-Wl,-O1"
LINGUAS="de"
MAKEOPTS="-j2"
PKGDIR="/media/linux_data/portage-pkg/"
PORTAGE_CONFIGROOT="/"
PORTAGE_RSYNC_EXTRA_OPTS="--quiet -z"
PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --compress --force --whole-file --delete --stats --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
PORTDIR_OVERLAY="/usr/local/overlay/java-overlay /usr/local/overlay/sunrise /usr/local/overlay/kde-testing /usr/local/portage /usr/local/overlay"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="X a52 aac acl acpi alsa amd64 apache2 audiofile bash-completion berkdb bluetooth branding bzip2 cairo cdda cddb cdparanoia cdr cli cpudetection cracklib crypt cups curl dbus dga directfb dri dts dvd dvdr eds emboss encode evo exif fam fbcon ffmpeg firefox flac fortran gdbm gif glib glitz gpm gtk hal iconv idn isdnlog java java6 jpeg kde kde4 kpathsea libnotify libsamplerate live lm_sensors lzo mad midi mikmod mmx mng mp2 mp3 mp4 mpeg mplayer mudflap multilib musepack mysql ncurses networkmanager nls nptl nptlonly nsplugin offensive ogg opengl openmp openssl pam pcre pdf perl phonon php png policykit ppds pppd python qt3support qt4 rar readline reflection samba semantic-desktop session sndfile spell spl sqlite sse sse2 ssl startup-notification subversion svg sysfs syslog taglib tcpd tga theora thumbnail tiff truetype unicode usb vcd vim-pager vim-syntax vim-with-x vorbis wavpack x264 xcomposite xft xine xinetd xml xorg xpm xscreensaver xulrunner xv xvid xvmc" ALSA_CARDS="emu10k1" ALSA_PCM_PLUGINS="adpcm alaw asym copy dmix dshare dsnoop empty extplug file hooks iec958 ioplug ladspa lfloat linear meter mmap_emul mulaw multi null plug rate route share shm softvol" APACHE2_MODULES="actions alias auth_basic authn_alias authn_anon authn_dbm authn_default authn_file authz_dbm authz_default authz_groupfile authz_host authz_owner authz_user autoindex cache dav dav_fs dav_lock deflate dir disk_cache env expires ext_filter file_cache filter headers include info log_config logio mem_cache mime mime_magic negotiation rewrite setenvif speling status unique_id userdir usertrack vhost_alias auth_digest" APACHE2_MPMS="prefork" ELIBC="glibc" INPUT_DEVICES="keyboard mouse evdev" KERNEL="linux" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LINGUAS="de" USERLAND="GNU" VIDEO_CARDS="nvidia vesa"
Unset:  CPPFLAGS, CTARGET, FFLAGS, INSTALL_MASK, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS

Firefox was built with these use flags:
www-client/mozilla-firefox-3.5.2-r1  USE="alsa dbus java startup-notification -bindist -custom-optimization -gnome -iceweasel -mozdevelop -restrict-javascript" LINGUAS="de -af -ar -as -be -bg -bn -bn_BD -bn_IN -ca -cs -cy -da -el -en -en_GB -en_US -eo -es -es_AR -es_CL -es_ES -es_MX -et -eu -fa -fi -fr -fy -fy_NL -ga -ga_IE -gl -gu -gu_IN -he -hi -hi_IN -hr -hu -id -is -it -ja -ka -kk -kn -ko -ku -lt -lv -mk -ml -mn -mr -nb -nb_NO -nl -nn -nn_NO -oc -or -pa -pa_IN -pl -pt -pt_BR -pt_PT -rm -ro -ru -si -sk -sl -sq -sr -sv -sv_SE -ta -ta_LK -te -th -tr -uk -vi -zh_CN -zh_TW"

Could there be anything kde 4.x related that prevents firefox from closing cleanly?