At the end of last year I mentioned in my Help with Minefield Error post I was getting odd error messages when I exited Minefield. I got a response in the thread I had posted over on Firefox Builds. Someone suggested disabling/removing the talkback extension has they too were getting similar problems with the newer version (3.0a2pre). After disabling the extension, I closed Minefield, restarted Minefield updated to the latest nightly build, closed and restarted Minefield to apply the update and then finally closed Minefield again. No Windows error messages! The only downside is I won’t be able to report crashes.