Everytime when I edit the monitor preferences in AMD to multi-monitor or to a multidesktop, when I press save or apply the program just closes with no errors and the preferences hasn't been saved. If I try to do it via the Displays app that is built-in in ubuntu 11.10 I get the following error:
The selected configuration for displays could not be applied
required virtual size does not fit available size: requested=(2560, 1024), minimum=(320, 200), maximum=(1280, 1280)
I don't know if it helps but my graphics card is a ATI Radeon HD 4800 and my monitors are both 1280x1024. I'm running the proprietary driver without post-release updates because I always get an error trying to install that one.