Hi, I have an older iMac, with 10.6.8 and the latest version of Firefox. My computer kept crashing in the past couple of months and I finally figured out that Firefox is the reason. When I use Firefox it will eventually cause the screen to go crazy. Most often I see white flashes across the bottom of the screen, or some horizontal lines. Sometimes large pixels and other times multiple images of my screen superimposed over each other. When that happens the entire computer is frozen and I have to hold down the power button to force shut down. For the past few days I've used Safari and Chrome and had no crashes. I deleted Firefox, emptied trash and reinstalled from a fresh download. I experienced a crash shortly after I started using the reinstalled Firefox. Please advise. Thanks...