I have an issue with file access as well. I have some MS Word file in a directory, and I changed the ownership for these files in the web interface of the DNS from "all users" to a specific user. From then on, I could not open the files any more, even if I change the ownership back to "all users". The error message I get on the Windows 7 machines is this: "you require permission from unix user\nobody to access this file."
I googled the message and I get that this is a file permission problem in Unix/windows. THe recommendation is to go in with telnet and change the file permissions with the chown command. However, I suddenly get \ another problem, which may be unrelated. When I try to login to the DNS323 via putty, I could do this as root, with my usual password. After rebooting the DNS, it does not allow me access any more with that same root user password. What is going on?