I discovered that deleting the Jabber GTalk account and replacing it with a full Google account solves the problem, so it looks like a bad interaction with the gabble ---> signond --> google-talkplugin combination.
I discovered that deleting the Jabber GTalk account and replacing it with a full Google account solves the problem, so it looks like a bad interaction with the gabble ---> signond --> google-talkplugin combination.