How I got a Trojan virus?

Most likley the download.

Here is the removal guide, scroll down to the automated removal instructions, and follow exactly as written.

http://www.bleepingcomputer.com/virus-removal/remo...

Crapafee will not remove this rogue.

Yes, you may get it from what you may think is a video program trying to update.. such as Adobe Flash player. You may have clicked on something like that without knowing and it downloaded the Trojan that installed Smart Fortress 2012. Happens all the time unfortunatly. The way I was able to remove it was through finding and deleting all of the Smart Fortress 2012 files and entries http://www.spywareremove.com/removesmartfortress20...

The trick is, boot your PC into Safe Mode (use the F8 key when you reboot - press sevearl times until you see the options on the DOS screen). After that, find all of the assocaited files and delete them.

If the manual removal is too difficult, you can always try an antimalware program to detect and remove Smart Fortress 2012 for you. Just make sure the program has been updated with the latest detection files.

The download is probably where you got the virus, by downloading you are saving files to the hard drive, by saving these files there, they can now run and change/alter the system. Only download from safe sites. Check ratings before you download, and always use caution when surfing the web, if a website looks suspicious then don't download from it. Use common sense.

Probably the download. You could check your anti-virus and see if it tells you where it came from (under report or something similar like that). It might not be from either. You could have something that isn't updated like Java and trojans and viruses are getting into your computer from there. (I haven't updated Java in years and I sometimes get trojans through Java once in a great while). Hope this helped a little.

It might have been both.

My personal bet is on the Video Stream

when you download things dont click on run, click on save thn scan it before you open and run it.