Greg is right. One topic at a time is best. Usually. . .
- Icons reverting to a previous arrangement while only using one monitor.
- Icons jumping to a different monitor.
- Icons re-arranging when disconnecting another monitor.
- Icons scrolling off of the viewable screen.
These are all mostly separate issues with desperate causes. They are all probably related.
Thoughts:
Windows Desktop is, at its root, is a folder like "Documents" or "Music". It has some unique properties that make it display as the desktop we all depend on. Having the ability to re-arrange in the folder columns as we see fit, and automaticly rearrange on the desktop to fit all in a smaller resolution when we need it has got to be complex, and aparently has conflicting functionality that manifests across multiple Windows platforms, complicated by Manny different video drivers with different functionality.
My solution to scenario #1 above was to use an app that records your Desktop arrangement and allows you to restore it with a right click menu option on the desktop.
"Desktop Restore" by Jamie O'Connel.