Have you installed new hardware before. You say you didn't install your printer so I don't know if you know anything about installing hardware. If you do then it is real basic. Before plugging in your mouse boot up your computer. When it is running plug in the mouse. You should get a "found new hardware" box on your desktop and it will ask if you want to install. You would say yes and follow the instructions. Hopefully your USB mouse came with a CD that have drivers for your mouse use that instead of searching your C drive for drivers - they will be old outdate. Once it is installed you will find your touchpad no longer works. That is only when the mouse is plugged in. Once the mouse is working - maybe not well but working go to the Control Panel and click on Mouse. There you can configure some of the functions of the mouse so it works more to your liking.
If you need further help email me with specific questions.
