Thanks for the reply.
'Use a proxy server' was unticked. AdwCleaner is currently scanning.
Earlier, to get back onto Internet Explorer, I did a system restore to three days ago. The problem with Google Chrome and Norton Internet Security remained the same though.
Another note on Browsedefender - Yahoo Community Smartbar is a constant feature in 'Uninstall or change a program'. Every time I uninstall it, it returns the next time I open 'Uninstall or change a program'.