What can you do if your antivirus software (in this case Norton) identifies a program as a Trojan, but you're pretty sure it's not?
Norton may have indeed given you a false positive when it warned you that a program was malware. But it's just as likely -maybe even more so - that Norton's mistake came when it told you that your hard drive was clean.
And I'm not knocking Norton here. These issues apply to every antivirus program in existence.
If your antivirus program identified something as a Trojan before you ran it, and found no infections afterwards, there's a very good chance that the malware is protecting itself from security software. That's pretty common behavior.