I am currently trying to get from "Twin View" to using separate X screen's on Ubuntu 12.10, however I'm not having a great deal of luck.
I am using an Nvidia GeForce GTX 550 Ti and am on driver version 304.51
Initially, when I turn on the separate X screens option, presents me on the 1 monitor with a box to accept the changes, however the 2nd screen goes black, and effectively, Ubuntu only seems to recognise the one screen.
When I reboot, I boots back into Ubuntu with both screens working in Twinview.
I'm not too sure where to start, but my xrandr can be found: Xrandr
Any help is greatly appreciated, this is the last but one thing I need to make Ubuntu my only OS, so fingers crossed we can crack it :)