[HELP] Computer Keeps Crashing!

Hello everyone. So in September of 2012, I got a new desktop computer for my birthday. I was hoping to play GTA IV on it sometime soon. Before getting the game, that same day, I was going online to search some mods that I could possibly enjoy while playing. I don't know what mod it was exactly (I think it was a fire truck model), my antivirus software said that there was a virus on that file and it was in the process of being removed from my computer. So I hit continue, then my computer freezes, then comes up a blue screen. I saw this note saying that it was an "NTFS.sys" error. I did some research about it and I found out that it is an audio error. Everytime I boot up my computer, it crashes after like 30 seconds. Does anyone know how to resolve this problem. I don't feel like going to Geek Squad and spending tons of money for something I could have done myself.