Firefox 3.6 Bug?

So I’m perplexed. Every time I startup Firefox 3.6 on my mac I lose the last folder in the bookmarks toolbar. Moving it out of the toolbar and back in fixes it until the next time I start the browser. Anyone else seen this? How have you fixed it?

Take note of the "Web Dev" folder in the toolbar on the left. Notice it doesn't actually show up in the toolbar.