I'm using Empathy on my Ubuntu (13.10) and sometimes when I receive the first message, it open the windows, but doesn't show any message, only the "-1 not readed".
Any idea what that means?
it's a bug i believe. The workaround is to close the window, open empathy and double-click on the contact name to open a new window. The text will then show up.
Please, sign in on launchpad and add yourself to the bug https://bugs.launchpad.net/indicator-messages/+bug/1019609, it will add some weight so it gets fixed faster :)