I am running Ubuntu 12.10. I have two displays on my computer: the builtin screen of the laptop and a television attached through HDMI. I go into the Displays setup panel and turn off mirroring, but when I attempt to apply the configuration I get the message:

required virtual size does not fit available size: requested=(2560, 768), minimum=(320, 200), maximum=(1600, 1600)

How do I change the maximum?