that sounds like the bug I read about. Well smart layers actually link to external files not sure if smart filters are doing external or internal file linking. I don't use Photoshop much any more.
sounds like Randy is on track - if elements within a file are known by the OS to link to another location then windows will protect the file by not letting you move any component.
I tried thinking of a real world analogy, even a bad one, but failed.
