I am having this problem as well. We just recently upgraded our servers to Windows Server 2003 R2, and ever since we randomly get files that turn read-only while a user is working in the file. We are using AutoCAD 2002 on Windows XP and Windows 2000 computers. This problem never happened while using Windows Server 2000. I have not been able to determine a common item on the computers that it happens to. We did have DFS running, but I have turned that off.
Has anyone come up with a solution to this issue yet?
The other issue that we have noticed is that files will also randomly disappear, and sometimes after a user has saved a file, closes AutoCAD and then reopens the file that the changes were not saved.