I have just recently noticed this problem occurring. When I receive an email, the on-screen notification bubbles 'keep popping up'. By this, I mean it will pop-up and tell me I have received an email, then it will disappear, and an identical bubble, telling me about the same email, will pop-up again. This will happen anywhere between 4-9 times. As you can imagine, it is getting pretty annoying, especially considering the volume of emails one receives these days.
I have ubuntu 12.04, and have installed notify-OSD, but have only used it to change the position and 'click to dismiss' properties of the bubbles. I have thunderbird (with my gmail account in it) and lightning installed (but only use TB to interact with my gmail calendar). I also use Chromium to check my gmail.
Has anyone got any ideas of what may be causing this? Is it a Chromium extension problem, or a thunderbird problem, or an OS/notification daemon problem?