I assume you don't have a "Re-Set" button....
Some PCs will shut down if you push and hold the "On"
swith for 4-5 seconds. If this doesn't do it, you can
turn off the switch that is near the point where you plug
in the PC. If not, you can always unplug the PC.
It's very likey the downloaded grand theft auto vice city
on kazaa is causing the problem. Once the PC is off, try
booting up again and see if you can now find it in "Add
or Remove Programs" (Click "Start", then "Settings"
then "Control Panel": you will find "Add or Remove
Programs" in the control panel.
Click "Add or Remove Programs" and it will display a list
of the items you can delete. Sometimes, malicious people
will add virus-like items to programs just to mess your
system up. They may have named the program something
different so it does not show up as "Grand Theft Auto".
Lokk for a program that was installed when you downloaded
the game and see if that's it.
Select it and click to remove it (It may say "Add/Remove"
depending on what version of windows you have). This
should be the end of it.
If you can't boot up, you may have to do this in "safe
mode". Re-start the PC and while booting up, hold the F8
key. You will get to a screen that offers "Normal", Safe
Mode, etc. Select Safe Mode and do the above.
If still no joy, you may have imported an actual virus
with the game, in which case, run your anti-virus program.
If you don't have an anti-virus but you can get into safe
mode as described above, hopefully you'll be able to get
online with your PC.
If so, go to
www.pandasoftware.com. They have a free on-
line virus disinfection service (Panda Active Scan).
Download it and it will scan your system AND rid it of
any viruses it does have.
Hopefully the above will handle this. If not, there are
more complicated approaches, but try the above first.