This fix works around the issue of Firefox randomly selecting “Change Search Settings” to search for the entered string in Firefox Settings when you want to search the web with the default search engine. When this happens you also lose the search string and have to retype it.
Place the following code in userContent.css or userChrome.css and place it in the chrome (lower case) folder within the Firefox default profile directory. If the chrome folder does not exist then create it.
* Update: best to have both userContent.css and userChrome.css in chrome folder as it is noticed that some pages,