If you believe your computer is infected and you don't have anti-virus
software installed, you should not install any now. (You don't want
your anti-virus software to become infected upon install!) Instead try
a free on-line scanner like Trend Microsystem's Housecall.
If you are unable to get your computer cleaned and/or the virus has
caused significant damage, you may need assistance from a computer
support professional like Remote-Technician.
Have you had any viruses recently?