xorg external monitor display problem

[David Mackintosh]

Kind of a specialized question here, I can't find anything on the web
which matches my problem.
 
I have this new Dell D600 laptop which I have installed FC2 on.  It
has a SXVGA+ (ie, 1400x1050) display.  X will display at this
resolution (at 24-bit depth) on the LCD display, no problem.
However, when I plug the laptop into a docking station which has an
Acer 77e 17" monitor attached to it, the Acer displays the 1400x1050
desktop, as viewed through a panning 640x480 window.

Experimentation has shown that the presence or absence of the dock
(ie just plugging the Acer straight into the back of the Dell) makes
no difference.
 
I know it is possible to have this monitor display 1400x1050x24 --
Windows does it.  I've also driven this monitor at 1600x1280x24 when
attached to a different linux system.  I also know that it is
possible to have this Linux display properly at this resolution on an
external monitor -- I have a Sony G400 at the office which does it.

I have gone through the FC2 System Settings -> Display applet
and have explicitly defined my monitor as an AcerView 77e.  I have confirmed
in my /etc/X11/xorg.conf that there is an appropriate monitor defined:

Section "Monitor"
        Identifier   "Monitor0"
        VendorName   "Monitor Vendor"
        ModelName    "Acer 77e"
        HorizSync    30.0 - 72.0
        VertRefresh  50.0 - 120.0
EndSection

The presence and/or absence of this section doesn't appear to change anything.

When I boot the laptop at the office, it is connected to the Sony G400 and it does
the appropriate thing.  At home, it still does not behave with the Acer.

In the Xorg.0.log, I've noticed that when connected to the Sony, the log reports:

(II) RADEON(0): Displays Detected: Monitor1--Type 2, Monitor2--Type 1

(II) RADEON(0): Monitor2 EDID data ---------------------------
(II) RADEON(0): Manufacturer: SNY  Model: 290  Serial#: 8011257
(II) RADEON(0): Year: 2000  Week: 25
(II) RADEON(0): EDID Version: 1.2
[...lots of monitor stuff trimmed...]
(II) RADEON(0): End of Monitor2 EDID data --------------------
(II) RADEON(0):
(II) RADEON(0): Primary Display == Type 2
(II) RADEON(0): Clone Display == Type 1

...which tells me that it is detecting the Sony all by itself and
making appropriate assumptions.  Where as when it is connected ot the
Acer, I see:

(II) RADEON(0): Displays Detected: Monitor1--Type 2, Monitor2--Type 1

(II) RADEON(0):
(II) RADEON(0): Primary Display == Type 2
(II) RADEON(0): Clone Display == Type 1

...which tells me that either the Acer isn't detected at all, or it
is detected improperly.  However, I still don't know what to do about
it.  I'm starting to suspect that the config file is merely there for
my amusement and xorg is trying to auto-detect things at startup
rather than read the config file.

What I can't find is an explanation as to why I'm getting this 640x480
on an external monitor which is clearly capable of displaying much more, nor
an explanation of how to fix it.  All pages on the web I've found suggest
that it means that my monitor can't run the video mode I selected (known
to be false) or that my video card can't run the video mode I selected
(also known to be false).  It has to be a configuration problem.

Incidentally, a co-worker has the same problem, only he's started with
FC2 and done an "upgrade" install to FC3.

Any ideas what I should begin looking for?

People interested in the complete contents of my xorg.conf file, and/or
the log files showing what happens when the Acer, Sony, or nothing is
plugged into the computer can find them attached to the snip at

http://xdroop.dhs.org/space/Linux/Dell+D600+External+Monitor

Thanks for any comments or guidance.

-- 
 /\oo/\
/ /()\ \ David Mackintosh | Public Key: 
         dave at xdroop.com  | http://www.xdroop.com/dave/gpg.html
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         Mystery attachment?  http://xdroop.dhs.org/space/GPG
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