Think you're talkinb about the "DELL 2005 FPW", don't you? Got the same problem some time ago. Unfortunatelly I didn't know anything about the graphical configuration tool you're using, but you can also manually edit your "/etc/X11/xorg.conf".
1. The following lines to it:
Code:
Section "Modes"
Identifier "16:10"
ModeLine "1680x1050" 119.06 1680 1728 1760 1840 1050 1053 1059 1080 -HSync +VSync
EndSection
Then add the following line to your "Monitor" section
In the "Screen" section make sure you've put in the desired resolution.
My full xorg.conf can be found here:
http://sinotech.dyndns.org/linux/xorg.conf
Regards,
Sino