There is always a problem in firefox when you install any software without any caution it will install a toolbar and also a default search in the address bar of the FireFox browser. Sometimes it leads to uninstall the brower. To avoid that we have some steps.
Type about:config in the url bar of the firefox
This will display a list some thing similar to this.
Accept the warning
Then it will dispaly this:
Then type keyword.url the filter text box of the website
Then restart your browser.