If you have a previous version of Firefox before Version 1.5, I strongly suggest you uninstall it and then install 1.5 or newer. Once Firefox 1.5 is installed, you can then use the automatic update features of Firefox to keep it up to date quickly and easily. Uninstalling Firefox doesn't remove your bookmarks or settings/tweaks by default. However uninstalling and cleaning out all the Firefox files is also a good way of resolving any extremely strange behavior or annoying problems you may get with Firefox. In any case, if you want to completely remove all traces of Firefox from your system follow these steps:
1. Go to Windows Control Panel>Add/Remove Programs, and if a 'Mozilla Firefox' entry (or similar) exists, select it and click Change/Remove and uninstall it. Note, you can also uninstall Firefox by going to the \Program Files\Mozilla Firefox\uninstall\ directory and running the UinstallFirefox.exe file. Reboot if required.
2. Go to your Documents and Settings\[username]\Application Data\Mozilla directory and delete the entire \Firefox subdirectory and all of its contents. Note that this will delete all of your bookmarks and saved settings. If you want to backup any or all of your current Profile, see the Customizing Firefox section first.
3. Go to your \Program Files\Mozilla Firefox\ directory and delete it and all of its contents.
4. Using a registry cleaner like RegCleaner 4.3, find and remove all Firefox/Mozilla-related entries (usually there are several Mozilla entries to be found) and remove them. Alternatively you can use the Registry Editor (Start>Run>Regedit) and delete the following keys - that is, right click on their name in the left pane of Registry Editor and select Delete:
[HKEY_CLASSES_ROOT\FirefoxHTML]
[HKEY_CURRENT_USER\Software\Classes\Applications\firefox.exe]
[HKEY_CURRENT_USER\Software\Mozilla]
[HKEY_CURRENT_USER\Software\MozillaPlugins]
[HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla]
[HKEY_LOCAL_MACHINE\SOFTWARE\mozilla.org]
[HKEY_LOCAL_MACHINE\SOFTWARE\MozillaPlugins]
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