We just discovered this problem today.
Both users on Windows 7 64-bit.
Pro user has 9.4.4. (Version drop-down doesn't have that option yet.)
Reader user has 9.4.1.
Source file is InDesign CS5 7.0.4, which both have, although one has stand-alone and the Pro user as the CS5 Design Premium package.
Reader user generates new PDF from InDesign. Wants to save in folder, replacing existing PDF, which was last edited by Pro user.
Cannot be done. States Pro user "owns" it!
This file has no security on it. No Windows permissions indicate a problem. No files open on anyone's machine. Even stopped all processes in Task Manager.
We cannot figure out whether this is an InDesign problem, an Acrobat problem, or a Windows problem!
Saving and replacing a file is not an unusual step. Why should this not work? We're really stumped! Found nothing in archives, but it was also hard to find the right keywords.
Thanks.
Search for help on Windows 7 file permissions and inheritance for how to set up multi-user access to folders.