White screen after running "startx"

I downloaded the BT4 final iso and burned it to a DVD and booted up from it. I try booting into one of the modes (tried multiple) and tried running "startx" to get into the GUI. It will start working to load everything up, my drive is spinning, but it gets stuck on a white screen and just sits there. I believe I need to download some display drivers possibly? I have an ATI HD4850. If drivers are the issue, how would I update them so I can get past this white screen?

Thanks

More than likely you are correct about needing drivers for your ATI card. I don't own any ATI/AMD cards but a simple google search will eventually lead you to what you need. At the main screen where you would type "startx" you could also try typing in "fix-vesa" and then "startx" which should help you get by in the mean time.