Howdy folks,
I've been using Poser 4 for quite a while now on several different machines.  I ran it for the first time in a little while, and it fails to work.

The symptoms are that the preview window appears to be white, with a fixed-size square in the upper-left hand corner the color of the background color.  No objects (figures, ground planes, etc.) are visible in the window, regardless of which camera is used or what orientation it has.  Rendering the scene locks Poser while calculating the shadow map.

Poser had been running on this machine for over a year prior to this happening.  Here are some of the changes that occured since the last time Poser had been successfully run:
Upgraded video card to GeForce 8800 GTS.
Increased RAM to 2GB; virtual memory to 6GB.
Now running dual-monitors, 22" widescreen @1680x1050 and 19" standard @1280x1024.

The operating system for this machine is Windows XP Pro, so that shouldn't be the issue.

Anyone have any ideas?