Virus stops Hijackthis in safemode from running, and stops Firefox/explorer

Hi there people, I’ve just got a nasty virus that got past norton antivirus and infected my system.
I tried desinfecting but norton doesnt do it, doesnt even find it. I tried hijack this but the trojan/virus stops it from running, i tried googling for hijack this but the virus shuts down explorer/firefox as soon as i try clicking on anything that has to do with common antivirus programs and hijackthis. Now i tried all of this in safe mode with networking as well, same thing there. So im basically stuck.

I have no idea what to do now, can anyone perhaps give me the name of a very good but not so well known anti virus program?