Analog - Out of Range.....going to higher video res

After modifying xorg.conf file to increase video resolution (1440x900) the monitor goes black and displays:


ANALOG
OUT OF RANGE
80.8 KHz 65 Hz

After changing xorg file and ctrl-alt backspace the system comes up to the sign on screen with the higher resolution. After I sign on the monitor displays the above information. I must then revert to original xorg file.

Here is monitor section of xorg:

Section "Monitor"
Identifier "Monitor0"
VendorName "Unknown"
ModelName "Unknown"
HorizSync 30.0 - 83.0
VertRefresh 56.0 - 75.0
Option "DPMS"
EndSection

I am running 8.10 Ubuntu Linux. Any ideas appreciated.

Ed