What reason do you have to use System Restore that often? Using System Restore can cause your Firefox installation to get corrupted because not all files are restored (only files in a white-list), so be cautious with using System Restore. *You may lose data in the Firefox profile folder like .js and .ini and .html files. *You may need to (re)install software that was affected. In case you need to reinstall Firefox then you need to delete the Firefox program folder before reinstalling to make sure that all files get replaced.