On my desktop PC I've been using Kubuntu 10.04 for about a year. Recently I've updated Firefox to version 4 using aptitude and the mozilla-team/firefox-stable repository.

Since then, I can't run it when I'm logged in through a VNC session. Firefox crashes immediately: when I try to run it from the console I get this error:

###!!! ABORT: X_ShmPutImage: BadShmSeg (invalid shared segment parameter); 3 requests ago: file /build/buildd/firefox-4.0.1+build1+nobinonly/build-tree/mozilla/toolkit/xre/nsX11ErrorHandler.cpp, line 203
###!!! ABORT: X_ShmPutImage: BadShmSeg (invalid shared segment parameter); 3 requests ago: file /build/buildd/firefox-4.0.1+build1+nobinonly/build-tree/mozilla/toolkit/xre/nsX11ErrorHandler.cpp, line 203

Firefox works fine when I run it directly from the PC. Firefox 3.x worked fine also from a VNC session. I tried to turn off the hardware acceleration from the Firefox preferences, but that doesn't fix the problem.

firefox --sync, firefox -safe-mode and firefox -ProfileManager also crash the same way.

Any idea how to troubleshoot this? Thanks.

Edit: additional info.

I run vnc (RealVNC 4.1.1) from xinetd, this is the config I use:

service Xvnc
{
        type = UNLISTED
        disable = no
        socket_type = stream
        protocol = tcp
        wait = yes
        user = root
        server = /usr/bin/Xvnc4
        server_args = -inetd :1 -desktop vnc5901 -query localhost -geometry 1160x675 -depth 16 -once -DisconnectClients=0 -NeverShared passwordFile=/path/to/vnc/password -render
        port = 5901
}