Webroot Spy Sweeper will keep the homepage from being reset. Download and run the free version of Spy Sweeper, then go into Control Panel -> Internet Options, and make sure the homepage is what it's supposed to be. Should solve the homepage problem.
McAfee has a free antivirus search page at:
http://us.mcafee.com/root/mfs/default.asp?cid=9435
You might want to bookmark that..
Norton ain't so good anymore.