I can confirm this in current edgy: ati radeon 9200, merged fb clone, xrandr stops working sometimes after disconnecting the external monitor. Other times it works fine. Could be sleep related (I can't rule it out, because I have had the system suspended before the error occurs).
** Changed in: xserver-xorg-video-ati (Ubuntu) Status: Unconfirmed => Confirmed -- RandR stops working with MergedFB when the external display is disconnected https://launchpad.net/bugs/37444 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs