I'm not very familiar with the Firefox codebase either, but I can suggest that a good place to start might be the differences between the Ubuntu build and the official release, since we aren't seeing the problems with other builds or with the official builds.
I'm not very familiar with the Firefox codebase either, but I can suggest that a good place to start might be the differences between the Ubuntu build and the official release, since we aren't seeing the problems with other builds or with the official builds.