Have you ever gotten so used to certain key bindings that when they're suddenly not working you can't hardly contain your frustration? I just experienced this and thought that it might help someone else so I'm posting this info.
I spend a lot of time using GMail with Firefox. So much so, that I have gotten really used to all the key bindings for GMail, especially those from Better GMail 2 (if you haven't checked this out yet you should do it NOW!). Well today I just upgraded to a newer MacBook Pro so I had to install much of the software I use. Firefox and all of the plugins I use was on the list. After installing this and starting to use GMail, I could no longer use the tab key to get to the send button when composing a message. Hitting the tab key would just pop to the top of the page and place the cursor on the browser command line. After a few minutes of Googling and finding nothing, I remembered Better GMail 2.
After actually going into the Better GMail 2 prefs and selecting the options I like, I again had the functionality I expected from the tab key. Phew, I'm again sane.
WARNING - Adult Humor
BTW, upon searching Google Images for the Firefox logo for this post, I discovered a new Firefox logo. Click on the link above to see the search results.