Not normal. You probably got a bad connection, but the update is not what you want. You are so far behind at Firefox 3.6.10 that even if the update worked you would still probably have to do more updates. With Mac OS X 10.4 you cannot go to Firefox 4.0, but you will want to go to the latest 3.6 version which is 3.6.17 Start at http://www.mozilla.com/firefox/all-older.html ''(those with current systems can upgrade to 4.0.1 at http://www.mozilla.com for 4.0.1)''. At the completion of the download don't let the setup start Firefox for you, when the setup ends, start Firefox in your normal manner this way you will be less likely to create a new profile. The extra startup pages are temporary -- read them. The next time Firefox comes up you should be back to starting with your normal home page. Note: Firefox must be down once the install starts. Close Firefox with File>Exit. Then make sure Firefox is not running -- On Windows: check the "Processes" tab in the Windows Task Manager. On Mac: Firefox > Quit then Command+option+Esc, if Firefox running use Force quit Permission errors on Mac: If you were getting permission errors on a Mac, download the latest Firefox version (for your system), then uninstall and reinstall Firefox. Do not remove your profile directories and files as they contain your settings, bookmarks, history, extensions, passwords, and cookies.