I did notice this previous post and the symptoms are pretty much the same. The only differences I think are the fact that I'm running non-virtual desktops (I forget what they are refered to) and that I don't have Auto Arrange turned on for my desktop. Turning the Workspace Manager off within Desktop Toolbox does cause things to work correctly - the icons are moved back on screen.
If I overlooked a post or you need additional information just let me know.
I have two additional desktops configured that are set to be created on my login. When I login the icons on my default desktop are enough to fill the first 2 columns of the screen to the full length of the screen (left hand side vertical). All icons are visible at this time. When the other two desktops are created the last 1 or 2 rows (I'd have to double check) of icons are no longer visible though there is available space shown on screen. They are moved off screen from what I can tell to a non visible position. In fact You can place an icon near the bottom of the screen that is almost completly off screen.
As in the thread I linked to in the previous post turning VDT Workspace Manager off corrects the problem and the icons are visible once again (after rebooting for the change to take effect). The difference between my situation and the specs posted in the linked thread above are these:
1) I did not originally have Auto Arrange turned on for my desktop properties. I do have Align to Grid turned on though.
2) Both my additional desktops are not "Virtual Desktops" they are the isolated ones (I forget what they are refered to).