I'm using AMD Catalyst on Ubuntu 12.10 on a Radeon HD 7570M. In single screen mode, there is a black cursor blinking on the left hand part of the screen. Sometimes (e.g. USB device connected), console text comes through and disappears half a second later.
In multi screen mode, the external screen shows nothing but grey and when the mouse gets into it, it gets trapped (dragging it back to the laptop screen where it comes from just sends it to the other edge of the external screen, so that returning to the internal one is not possible). When I activate the option Xinerama, I'm experiencing bad trouble too.
How do I get a working graphics card?