Normal
My first major infection was a fake antivirus trojan. I was younger and didn't know what it was at the time. Took a while to get rid of that bugger once I learned what a rouge AV is. My last one was probably a browser hijacker, that randomly appeared on my PC out of nowhere called mysearchdial. Even then that was a while ago and I still am extremely paranoid even today with what is out there. Human errors are inevitable though.