did you find the name of the trojan,malware/virus? and do the search for a fix? most peeps will reformat and start over, but I find it more fun to remove the little buggers from my system and not losing all my stuff. and as others posted above if you can not find your OS disk you are in deep do do. a lot of these antivirus websites have good step by step instrutions on how to remove unwanted spyware/malware and viruses. follow the steps and you should be ok. good luck to you in your endevour. Smitty of Hired Guns.
