Its something easy without anti virus
Go to START and RUN, type CMD.
Write CD.. and then enter
again write CD.. and Enter
Now write
CD WINDOWS and enter
now again CD system32 and enter
The last step is
Write SETUP and Enter
Wait a little bit if you don't get a box asking to move to your setup then you are infected...
NOTE : The SETUP who is inside system32 is closed if you are not infected
and open if you are infected
alot of virus have this format system.exe