m.exe and I cant install hijack this

I have a problem. On my home computer it was infected with a trojan qhost as per symantec. Whenever I put in a thumb drive, it changes the autorun to m.exe, and runs it and symantec catches it, and spybot stops the browser hijack, but its constant. I have cleared the hosts file, and ran their removal tool, which found nothing, so I found this site in my searches. When I searched for this stuff on that computer, it didnt find anything relevant, so I guess the hijack worked well.

I tried to install hijack this, it wont let me, it just closes, same as if I go to their site to download it, it just closes, even forums, it just wont let me go anywhere to fix it it seems. I am typing this on my laptop.

I saw the thread here about what to do to start, and I downloaded Malware Bytes AntiMalware- and I ran it and it removed about 300 items, then ran it again, and it found nothing, and theres no virus as per symantec, but its still infected, any removable drive that goes in gives me the autorun of m.exe, and then tries to change my search settings, which spybot stops, but its constant, and then symantec tells me theres a virus that it catches, m.exe but it never goes away. I cant install the new hijack this even with a rename, and I can not run the old version that I have installed either, so I am lost on that one. I need some help with this one.