One of the best features about Firefox is the about:config window. You can hack away and play with just about every aspect of the browser from there. Here is a guide I ran across that helps you use about:config to get rid of a few annoyances.
After installing Firefox, there are things I must do every time to make it behave sanely. Thank God for about:config. Strange how all of these things are disabling some feature of Firefox. Maybe Firefox tries to do too much.