Try a variety of free anti virus softwares and anti spyware utilities. I can recommend you ad aware http://www.lavasoftusa.com/ , spybot http://www.safer-networking.org/ , avg http://free.grisoft.com/, and anti vir http://www.free-av.com/ . Try Anti Vir first, avg second( if the problem persists), ad aware third, and spybot last.These utilities should remove the trojan, but if it doesn't you can always try to do a system restore or format your computer and install a fresh copy of Windows. To do a system restore, goto the start menu -> all programs -> accessories -> system tools -> system restore. Try to select a point that you remember that you didn't have that trojan. If none of these methods work, I believe a trial of kaspersky should do the trick.