When you install the ICQ instant messenger software, it hijacks all your browsers, add toolbars and replace the default Google search engine with the annoying ICQ Search. You will have to uninstall the add-on from your browser, uninstall the ICQ toolbar from you Control Panel – Add / Remove programs, but you will still have ICQ search when you type search terms directly to your address bar.
To restore it to Google Search, just try this:
Open up Firefox. Click on the address bar and type in about:config, then in the search bar type Keyword.url, under preference name double click on Keyword.url and copy and past this into the box
Then click Ok