You should download them directly from AMD's website, not a 3rd party. You might also need to be logged in as admin. You could need to wipe previous drivers from your system. A virus could also cause problems, or even a virus scanner may need to be disabled.
Download from here:http://support.amd.com/us/gpudownload/Pages/index.aspx?src=CCC-CheckForDriverUpdates
If it still fails, you could try to install them in safe mode. A virus scanner or some other software could be getting in the way, and safe mode will not load those items.