Run online scan using Kaspersky or ESET or A-squared online scanner:
http://www.kaspersky.com/virusscanner
http://www.eset.com/onlinescan/
http://www.emsisoft.com/en/software/ax/
See if any of these online scanner will detect and remove the said trojan horse from your computer.

If the problem continue, do this:
Get HijackThis from http://www.trendsecure.com/portal/en-US/_download/HiJackThis.exe
Create a folder in your desktop and save Hijackthis.exe on this new folder.

Open Hijackthis.exe, click "Do a system scan and save a logfile"
After the scan is finished, the notepad will open to display the log.
Copy the entire log information from the notepad to one (1) of the forums below:

1. http://www.lognrock.com/forum/index.php?showforum=5
2. http://forum.securitycadets.com/index.php?showforum=2
3. http://www.temerc.com/forums/viewforum.php?f=12
4. http://www.malwarebytes.org/forums/index.php?showforum=7
5. http://www.bleepingcomputer.com/forums/forum22.html

Let them diagnose or analyze your log file. Close HijackThis window (do not fix anything unless you receive instruction from the HJT analysts)