Comment 3 for bug 1278942

Sorry for the delay, there was a mad rush to get the 1.0.0 release ready.

Try this first, to be sure:
sudo apt-get install --reinstall libatk-adaptor

One more, this really shouldn't be necessary anymore, but I heard it helped occasionally:
add
GTK_MODULES=gail:atk-bridge
to
/etc/environment

So, do you have any firefox from the regular repository installed or are both, the stable too, from PPA's? Which PPA's? What about Thunderbird? Maybe they aren't built with ATK. I'd like to try them here.