First of all find and make a copy of your [[profiles|profile]] include all folders and sub files, and put it somewhere safe, the XP desktop is a suitable location. That allows you to restore settings and bookmarks etc after a re-install. *see [[backing up your information]] * http://kb.mozillazine.org/Profile_backup Firefox upgrades will normally install over the top of existing versions without any need to uninstall, but in your case it is probably worth deleting the program folder prior to installing as a clean install * see http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall One of your Crash IDs is giving a null signature, the crash is of a type that is not generating and submitting useful information [https://crash-stats.mozilla.com/report/index/cf3778b1-05f0-4636-9678-368932120202 cf3778b1-05f0-4636-9678-368932120202] Please take care to ensure you use a genuine copy of firefox from for instance getfirefox.com or http://www.mozilla.org/