Comment 2 for bug 273754

Thank you for taking the time to report this bug and helping to make Ubuntu better. This error appears to be a feature of Firefox. If you go to Edit -> Preferences -> Tabs , there is "Warn me when closing multiple tabs". Unchecking that stops both error screens. Also, if one checks "Do not ask next time" in the 'Quit Firefox' box that comes up, you will only receive one box because you are closing multiple tabs.