Permission Problem

Hello there,

running an xserve with 10.5.8 and in the last couple of month something strange happened. The system and the data are running separetely .. 3 Disks. 1 running the systems, 2 in a mirror RAID config. All the priviledges on the shared volume are set to Owner: root (R&W) Group: Staff (R&W) Others (R)

As I said all was running fine with files saving with correct permissions until some files started to have the group with only read permission.

I did discover later that the server changed the group to _unknown .. I did change the group back to staff and propagate permission to the disk but every time a client save a file from a program (be Word or photoshop or indesign or whatever) the file will assign only right permission to the Staff group.

Not sure what else I can try to change this. Any suggestion?

Server is running 10.5.8

thanks