Hi. It is unlikely that a virus did that. This points to a hardware failure. We can be talking about Video Card failure. The reason why I didn't tell you that as a first cause of your problem was because you have to make sure that the card is properly seated (especially if the computer is not brand new), clean, the video cable working, properly seated (the cable that connects your monitor to the PC) and with no pins bent (CHECK THAT), and that you don't have another expansion card causing conflict. Also, after checking all that, you can try is it is your video card by trying it in a different PC. One important question: Do you hear any beeps when you start your PC? IF so, how many? PAy attention to the pattern, like 2 shorts and one long beep, etc.., and write down the name of your BIOS manufacturer (Award, Phoenix,etc.) If you try those things and your video card is working, then it could be RAM or a Motherboard failure. You test RAM with this program "Memtest86". If you have access to the Internet from another computer, download it and create the bootable CD or Floppy Disk. Instert it in the drive and start the PC, it should start testing your RAM right away automatically but it takes hours. You can also test your RAM by pulling one stick at a time and start the PC and see if you get an error; then try the other one and the same thing, and also switch slots and the same procedure. Of course, you can try the sticks in another PC to make it faster, but make sure this other PC uses the same type, speed of memory. I don't wanna sofocate you with more info so go ahead and try and check all those things and post back with more information and results,ok? Good Luck!
Good Luck!