Firefox opens on my desktop, but I only get a popup small screen when I mouseover the Firefox icon in the taskbar; no full screen. How do I get the screen back? This happened very suddenly two days ago. I have to go through Windows to get on the internet, and I cannot access the Firefox home page to use any buttons or links. My laptop's OK, so I don't know what I may have done to cause the problem. I'm not tech savvy, so if you have a solution, please provide detailed instructions.