The topic says it all. I recently pacman -Syu'd and firefox has refused to start after this. I've tried rolling back to firefox 4 (and xulrunner 2) but I just get an error about XPCOM not loading.
Trying to start firefox 6 just yields hanging. I've tried running firefox with LD_DEBUG=all and I've uploaded it here: http://lusitania.logik.li/files/firefox.log . Any help would be appreciated. Pointers about how successfully rollback to firefox 4 are also an acceptable substitute.