I got startnow hijacker on my PC, too. I just found out a manual removal instruction . I have been tired of my antivirus because it spent my much money without doing its work properly Hope I can manually get rid of this pesky staff.
if this is the Startnow I am thinking about, removing it should be very easy - http://zugo.com/uninstall/
after you do that, change manually the home page to the one you want and restart your computer. That should solve the problem.
If not - go to your browser's tools/options then manage add-ons and remove the startnow toolbar add-on. Then change the home page again and restart your computer.