Office 2007 changes file permissions when saving on network

I recently upgraded to MS Office 2007 on our computers. Ever since I have had a very puzzling problem: whenever word or excel save a file (existing or new) on a network share, they change the permissions to read only.

I’m using Windows XP, Office 2007 professional on the clients, Linux with samba 3.0.30 on the server. Whatever the file permissions were before, after saving they are reset to 400 (user only, read only).

This problem is new to Office 2007, with the 2003 versions everything worked fine. Until now I have found no answers on the internet.

Does anybody recognize this problem? I’d very much appreciate any hints and tips!