Hello, anyone please help me.
When I have opened Google Chrome it popped up on a page navigation.iwatchavi.com that called NavSmart.
Navigation.iwatchavi.com is a browser hijacker.During installation it adds itself as your homepage and defaults search engine.
To remove NavSmart I suggests MalwareBytes Anti-Malware. In addition, use the free utilities Junkware Removal Tool and AdwCleaner. Download these free tools from here http://www.myantispyware.com/download/ or follow the guide.