[X4U] Desktop too large for display?

[Teddi Pomaika'i Stransky]

Mac Pro; 2 x 2.66 GHz Dual-Core Intel Xeon; 4 GB 667 MHz DDR2 
FB-DIMM; OS 10.4.10
21" ViewSonic Flatscreen (main video), 17" Dell flatscreen (side 
video - vertical)

First let me note that I was on the machine yesterday (12/22/07) 
almost all day and it was fine; I did some photo editing, set up 
several documents for the local church, chatted online with my 
sister, and played some games. Both monitors were up and running 
without issues. For much of the day I was playing a high-end 
video-intensive MMPORPG game (World of Warcraft) and had no glitches 
or problems. The machine shut down as normal, and to my knowledge 
there were no alien spacecraft or cosmic events in the neighborhood 
during the night.

This morning when I booted the machine, the display was bizarre. It 
appears that the desktop is too large for the screen; I have to 
'scroll' to the top of the screen to reach the Finder bar. As I move 
the mouse on the screen, the desktop image shifts to compensate ... 
i.e. if I move the mouse to the left, the desktop shifts to the 
right, and vice-versa in all directions, including diagonally. This 
is true whether I am on the desktop or in an application window, and 
affects both monitors. The constant swimming motion is actually 
nauseating, as I'm prone to vertigo due to inner-ear birth defects.

I checked all the display settings, as far as I could tell nothing 
had changed. I then tried changing them, but the same problem exists 
with different resolutions and display settings. After exhausting all 
the settings variations I could come up with; I got out my install 
disks. Booting from the install disk seemed to stabilize things, so I 
did an "Archive and Install" and rolled the machine back to the OS 
(10.4.8) which it had on delivery. That went fine to all appearances 
... but when I booted up after the install, the problem is still here.

Anybody seen this one before?  I've found nothing on the 
troubleshooting forums at Apple, but I've not come up with many 
appropriate search terms. "Desktop too large for display" brought 
nothing helpful.

Thanks in advance for your input.

Teddi
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