Hello, I don't have any specific idea, but try recompiling Firefox without any CFLAGS/CXXFLAGS set. Using another Flash implementation (Gnash/Adobe) might solve the problem too (or introduce new problems:). Also try cleaning up your Firefox profile (in terms of add-ons, most importantly).
-rz > [ebuild R ] www-client/mozilla-firefox-2.0.0.13 USE="ipv6 -bindist > -debug -filepicker -gnome -iceweasel -java > -mozdevelop -moznopango -restrict-javascript -xforms -xinerama -xprint" > LINGUAS="zh_CN -af -ar -be -bg -ca -cs -da -de > -el -en_GB -es -es_AR -es_ES -eu -fi -fr -fy -fy_NL -ga -ga_IE -gu -gu_IN -he > -hu -it -ja -ka -ko -ku -lt -mk -mn -nb > -nb_NO -nl -nn -nn_NO -pa -pa_IN -pl -pt -pt_BR -pt_PT -ro -ru -sk -sl -sv > -sv_SE -tr -uk -zh -zh_TW" 0 kB > > uname -a > Linux bobbin 2.6.24-gentoo-r3 #15 SMP Sun Mar 30 20:16:31 Local time zone > must be set--see zic i686 Intel(R) Core(TM)2 > CPU T5600 @ 1.83GHz GenuineIntel GNU/Linux -- gentoo-user@lists.gentoo.org mailing list