I had the 15 day key and it had no issues. Today the key ran out so I bought it and windows wants to tile it. I proceed to check center (in windows) and now I have the two pictures on each monitor (4 pics). When i goto next image its tiled again.

look
http://entertainment.webshots.com/photo/2512809830026801516wCIJdx

(Webshots is not on by the way)
What happened?

And now the solution.
Goto C:\Program Files\Display Fusion
Right Click DisplayFusion.exe
Select Proprties
Click the Compatability tab
Check Disable display scaling on high DPI settings
Kill Display Fusion in system tray
Run DisplayFusion.exe
Change the wallpaper

This is definitely the fix. I undid this and it was broke again.
Its a problem I'm guessing with Windows Aero in Vista, not sure.
Now as to why the trial worked then the registered didn't I haven't a clue.