Problem launching with Restore Previous Pages turned on.
For quite a few versions of FF, I usually have several updates for my plugins that are 'saved up' for the next launch. However, if FF is launched by clicking on a URL in another app, then FF opens the previous pages, opens the updated plugin pages, then FORGETS to open the URL that originally launched Firefox!
I'm only using 3 or 4 saved tabs, and have "You've updated Delicious Bookmarks" or similar pages also want to start up. This causes FF to forget the original URL for launching.
I'm also using a password for my FF keychain.
Hope this is clear: the launching goes well except for the original action that gets forgotten.