Hmm, not what I was hoping for but useful to know - thanks.
Is there a way to do it on individual machines? I tried creating lock files and putting them in certain folders and removing permissions in the hope that it would prevent parent folders from being moved but it didn't work. It only stopped the file from being moved out of the folder it was in.
There are only two problematic machines (or users...) so while not ideal something like this would be a suitable workaround.