Gemini48 Royce

I got a new computer; I downloaded SL and Firestorm viewer. When I login, the screen flickers and has various colors on the edges. The flickering is occurring on the edges and the text won't stay on the screen, flashes in and out. What is causing the flickering on this new computer that wasn't happening on my old one? How do I stop the flickering? There was a notice when I started Firestorm about graphics, but I'm not sure if I have to add or download something else.