|Laptops require drivers from the laptop manufacturer, not from the device manufacturer, because the hardware is custom made and only HP have the correct custom-made drivers.|
So try the graphics driver from HP for that model. Uninstall existing AMD driver first.
Incidentally, it's strange for that model to have DOS pre-installed. According to my research the Pavilion g6 series leaves the factory with Windows 7 pre-installed (and with drivers from HP).
Since you've installed a "clean" retail Windows 7 it's very likely many of the drivers that Windows Setup has installed are not exactly the right ones. Visit the HP website which serves your country and grab the correct drivers for that model.