I just had a very similar issue - I've been using dexpot in with display fusion (like ultra-mon, but less features). Anyway, when I tried to use dexpot to manage my desktop backgrounds, the system blue-screened on me. After I rebooted, desktop 1 had a blue screen and no icons. I could force it to show desktop from the taskbar, but as soon as I switched to any other desktop and then back to desktop 1, the blank screen would be back. I tried uninstalling/reinstalling dexpot, and this did not fix the problem. I was just about to give up and deal with it, but then I noticed the blank desktop was selectable, like a window. Grabbing a copy of sysinternals process explorer, I used the target function and found that for some reason office communicator had freaked out and taken up the whole screen. After that it was a simple matter of killing the process and restarting it.

Hope this helps anyone else having issues. :)