Same issue. Maybe a little more info:
I have a Pogoplug pro, 4 Windows 7 computers all running the software and 1 Mac mini running the software. When I set up the Mac, I had to choose what folders I wanted access to using the Pogoplug software. I created a new folder and selected it in the software. I can see the folder from all of my Windows 7 computers but can not write to that folder. I am not trying to share it with anyone just the main account. When I try to write to this folder, Windows prompts me that I need "permission to perform this action". I press ok and the same message pops up over and over. It is some Mac/ Unix / Pogoplug software permissions issue.