If I have a large amount of links in the "Today" folder of Bookmarks > Manage Bookmarks > Today I can make Firefox crash by copying all the "Today" link to another folder and click "Downloads" before the copy is complete. It may happen with any folder but I have not tested.
Steps to reproduce:
Open 30-50 pages so the links are listed in "Today"
Copy them by hilighting and dragging them to another temp bookmarks folder
Quickly click "Downloads" before the process is complete
Firefox will crash. This happens on a clean copy too.
Can anyone verify?