DO NOT JUST DELETE IT!!!! u will regret that.
i have never specifically heard of "trojan dropper", but on norton'* website there should be a patch to remove it... just look up the name.
btw i would disconnect that pc from the internet untill u got the problem fixed. and u need to figure out who gave u the trojan, dont download anything from that person again.... a trojan is used to allow someone remote access to your pc without your permission.