Installing AMD 8550g drivers caused issues after boot and "Hardware not supported" error

I downloaded the official .run file from AMD's website. After I installed it, when I booted my computer, only the terminal was available through Ctrl + alt + T. The screen was black with the watermark "Hardware not supported".

So I uninstalled fglrx drivers. When I booted up again, my side bar was flickering and I have some other screen issues too.

Can someone help me on how to install the correct drivers?

I am running Ubuntu 13.04 with a 64-bit processor.

Thought it would help to tell you that support for the 8550G, as far as I could tell, didn't start until Catalyst 13.10 so you'll need either 13.10 or 13.11. I've found them to be a real pain, using Linux Mint Mate 15, but it might be better for you. Installed via the .run from AMD's site.