I had the same problem with the graphics "static" when crossing into the autohide panel, and also complete graphics freezes when I used "Add To Panel".
My system is similar to yours, AMD quad core with Radeon GPU. I tried the open source fuglierx and the Catalyst. Both were horrible.
My "cure" for the problem was to wipe the partition and reinstall. I installed all updates, and the 3.4 kernel, but did not install the fuglier x driver. The graphics are fine, for me, without it.
I can't switch back to MATE - I like Cinnamon too much.
Linux Mint 16 Cinnamon (64 bit), Quad core AMD A8-3870 APU with Radeon HD Graphics 6550D, 8GB DDR3, 1600MHz
Microsoft-free environment since 1996