Indicator crashes when screensaver activates

[Hyogapag]

Well, actually I'm not sure it crashes when it activates, but I know that when I get my computer out from the screensaver, it has crashed. Actually, here's the story I can reproduce any time.
I open Thunderbird from the indicator, and it works fine. I let it reduced in the windows list so I can have notifications and so on. But, if I leave and that the screensaver activates, when I come back the indicator has crashed ie the little white arrowat the left of the icon, and so the informations usually displayed (Contacts, Compose e-mail, etc.) Also, the launcher from inside the indicator is inactive.
So, I close Thunderbird and launches it again : every things works again.

Tell me if you need more details.