There is a issue with Ubuntu 11.04 Natty Narwhal 64 bit and the compatability with my Radeon ATI Propriatery driver. I have a Radeon HD 4850 PCI Express Video Card. Note: I had no issue with Maverick Meerkat 10.10
The issue that happens, is as soon as I install this driver, I lose all input from my display, and I get "Input not available" on my screen.
Whole screen goes black while the OS works fine in the backround, only as soon as this driver is installed. I've wiped the system twice, and I am sure this is the problem.
Let me know what other information you guys may be interested in.