Ok. When your computer is first booting, before it hits the welcome to windows screen you want to hit F8. It can be kinda tricky the first time and you might have to restart several times to hit it just right. When you do get it, you will see a menu. One of the options will be Safe Mode. Let windows go through in safe mode. You may recieve a warning saying windows is working in safe mode, just click ok. Once windows is up right click on my computer and go to properties. Under there you should see a device manager unless you are running XP which means device manager is under hardware tab. Once in device manager you should see display adapater, click the little + next to it to expand it. If you see more then one thing under that, then you have duplicates. Just click on it and say remove. Do the same for your monitors section.