I was trying to determine if you needed to select the AMD graphics prior to installing the driver.
An ATI experienced person would have a better idea, but you may need to get some type of uninstaller for the ATI drivers, or uninstall the graphics controller and select remove all drivers when you do. I realize you uninstalled all drivers with driver sweeper, but maybe you uninstalled too much with that. I have never used it so hard to say, but I suppose the ATI forums you went to would have known the best procedure.
I do see comments about the Catalyst drivers, or the Control Center every now and then. Are you fairly sure the driver file you downloaded was good and does it have both the drivers and the Control Center, if that is how...