I can't get my switchable graphics cards working on my Acer 4820TG laptop. It came installed with Windows 7, but I've installed the RTM build of Windows 8. I have to keep the "Graphics" setting on the BIOS set to "Discrete," if it's set to "Switchable" the screen turns black after the boot animation is complete. The machine has an Intel graphics card and an AMD Mobility Radeon HD 5650, and I know that the Intel card is working. I've seen it work a couple of times with Windows 8 installed, but for some reason it just doesn't anymore. I know that it's not broken, because when I plug in a secondary monitor, and move the cursor to the right, I can see it on that monitor.
Are there drivers or something I need to install? I've tried a number of drivers and utilities from Acer's website, none of which have fixed the problem.