A box appeared in the UR corner of my screen, "Firefox 3.6.13 is available, with link to get it. Clicking the link, message is "there were problems checking for/dowloading/installing. . .because FAILED (UNK REASON). I can't get rid of the box. Went to Firefox site and downloaded version 8.0 but when I try to run it the message is "you must shut down Firefox" with an "ok" button. Firefox IS shut down but can't get past this point.
Firefox might still be running in the background. Right click in the task bar at the bottom of of Windows (next to the time and date) and select Task Manager. When the Task Manager opens, look at the running processes. If Firefox is still running you can end the process. Then try upgrading to FF 8 again.