System is infected by unknown trojan?

Dear Friends,

In my system ,if I open my computer or any other drives then following error messages displayed on the screen.

System Error

Your system is infected by unknown trojan. It's dangerouse for your system.Click ok to download antispyware programme.

I was scan the system with best 3-4 antivirus also I formatted and re-install windows XP but till problem is not solved.

So please please help me..

Thanks to all.

System is infected by unknown trojan?nortan antivirus

Damn.

Did you just formaed only C partition or entire hard drive? By now you should reformate your entire Hard Drive.

don't do a Quick Format, Make a full slow proccess format to kill everythings.

System is infected by unknown trojan?nortonantivirus

NFW you formatted the hard drive and still had Bull like that popping up,

Unless your problem lies on another partition try formatting them all