I have had more than a headache with HP notebooks and 7xxxm GPUs.
If I am not mistaken, I fixed one of them by updating the BIOS from the HP website, then uninstalling with Display Driver Uninstaller, and then installing the latest version of the driver from HP website. If that doesnt work, install the latest version from AMD. If it fails, try compatibility mode.
However, that workaround doesnt always work for some reason.