The prompt to ask whether or not I want to close multiple tabs is asking this regardless of the "warn me" checkbox and if I only have a single tab open. This seems to only occur when firefox has a single window open. In additional windows, created by clicking the "firefox" icon on my desktop and not made through the application, the behavior actually works as expected, e.g., firefox does not prompt when only one tab is open, it will prompt when more than one tab is open if the "warn me" checkbox is checked, and when clearing the checkbox, firefox will remember the setting - even if firefox is completely closed and then re-opened. When re-opened, the first window malfunctions but the second window behaves as expected - it remembered the settings from the previous session. Now here is the kicker - open a first window, then open a second, by clicking on the desktop icon (not from within the app). Now, close the first window you created. Now, the remaining 'second' window will actually malfunction, as if it was the first window opened. It seems to be something about that first instance that I can't quite put my finger on.