i have the same computer and i had the same problem; with automatic installation of windows updates and device drivers windows 8 would soon after installation install new drivers for the AMD/ATI card and my screen would go black.
Research
By plugging in monitors in all of the outputs ( hdmi and vga) i was able to get the picture back, the problem consists of many parts to my knowledge.
Dual screen regongizion
After the driver was installed i had 4 screens on the screen resolution view, 1 for vga output, 1 for hdmi output and 2 for the laptop screen, 1 for each grapichs card ( the AMD one and the Intel one integrated in the CPU).
Incorrectly disabled screens
When plugging in a external screen in hdmi output i would get image on my laptop screen aswell, the reason for this is assumed to be that the inserting of the HDMI cable would switch on the AMD card and thus the already enabled screen Laptop monitor ( AMD) would start sending images to the laptop screen. Enabling the laptop screen ( Intel) ( be aware of that there seemed to be a limit of how many screen could be enabled, so if you can't enable the correct screeen, try to disable some other ones) allowed me the the picture again on my laptop screen without having external monitors plugged in.
Still incorrect drivers
After doing all this and getting my screen back i could still not use switchable graphics since the drivers were not aware of the functionality. As such i set out to install the correct drivers. I simply downloaded the latest drivers off acers driver site for windows 7 x64 ( VGA AMD VGA Driver 8.771.1 197.0 MB 2011/07/06 , filename "VGA_AMD_8.771.1_W7x86W7x64_A.zip") judging by the filename this should also work for 32-bit version. by setting compability mode to windows 7 on the setup file i was able to install the drivers which so far seem to be working great for me.
Solution
Assuming you're about to install a fresh version of windows 8 and have a computer with switchable graphics card or are willing to reformat here's my proposed solution:
After naming your computer you get to choose wether to use express install mode or not, don't, instead disable windows update and automatic driver installs, after windows install finishes, go to your manufacturers support homepage and grab the latest drivers for your graphics, install them by running the installation under compability mode for windows 7. If you are not willing to reformat, try to retrace my steps through the Research part of this post.
Enjoy windows 8!
i kind of repair it but video card is still not recognized. here is my solution: i went into safemode, uninstall the latest updates, restart the machine (windows will keep on update to certain percent, does not matter, just wait) and on the restart you will see failure on configurng update, just wait long time... and you will finally go back to your previous version. hope it is helpful for others. it is quite logical, isnt it? :) – supernx – 2012-10-20T07:12:12.967