sighhhhhhh, May I suggest a five pound hammer? Take the hammer, dip it honey and breadcrumbs, its now in Trojan mode, point your index finger at the floor and proceed to smack the bejesus out of the Trojan, you will find his horse also, smack the high heaven out of the horse, thus, the trojan is now gone,

If you are talking about a trojan in a computer specifically the registry? Just run a good antivirus program.

http://download.cnet.com/AVG-Anti-Virus-Free-Edition-2011/3000-2239_4-10320142.html?tag=mncol;2

If it still perists, uninstall avg and try MSE, Microsoft Security Essentials.

http://www.microsoft.com/security/pc-security/mse.aspx

Another program that is very good is Malwarebytes Anti Malware.

http://download.cnet.com/Malwarebytes-Anti-Malware/3000-8022_4-10804572.html?tag=mncol;1

(All of the programs mentioned above are free. The only reason why it says about buying malwrebytes is for real time protection. Its not enabled in the free version.)

Hope this helps.

if your talking about a trogen in the HKRY files,use regedit to find it and delete it.a virus scanner should find and delete it but i missed 1 on mine using 4 different virus scanners.