Norton removed trojan - now I can't boot my laptop

I just installed a trial version of Norton and it found a trojan and a cookie tracker. However, after removing the trojan I am no longer able to start my computer. I can't even start in boot mode (F12 works, but not the safe mode).

How can I get around this to fix it?

 

I find it very annoying when a company offers a product and don't even have proper customer support, but refer people to sign up to a forum to get responses from OTHER customers! How utterly insane can that be?