Ubuntu encountered a fatal error

Hello,
I am trying to test out indicator-whether using the unstable builds under Ubuntu 10.10 Maverick Meerkat. Suddenly, I found my system stuck for a couple of times and I received the following error message when I tried to open banshee. It is very annoying to me and have spent many hours fixing it. I really need your assistance to resolve the following matter. Thanks in advance.

Encountered a fatal error
Exception has been thrown by the target of an invocation.
