Crazy issue to try to explain. And, I've got a wealth of details I could give--been working over this one for months.
I'll start with the user's perspective:
Windows XP User opens Excel. Save As.
Chooses a samba share (where user is in group that has rwx). Click's Save.
File appears with the specified name.
Window shows "The file {blah} exists. Do you want to replace the existing file?" (File name didn't exist before attempting this save.)
Choosing Yes -> File fsa727.tmp appears. (repeats will increment #)
-> Window says "Cannot save {full path}. Folder is marked 'Read Only'." Clicking OK drops back to save window.
Choosing No -> Drops back to save window (no .tmp created).
Opens Word. Save As.
Chooses same samba share.
File appears with the specified name.
File ~${name of file}.doc appears.
File ~WRD0000.tmp appears.
File ~WRD0001.tmp appears.
All files cannot be renamed/deleted (including the properly named file). "Access is denied."
Creates any kind of file (right-click -> new) in the samba share. Can not rename/delete. Access is denied.
Ok, now for some admin-side info.
*Many users in the same group (and only that group) have no trouble. Newly created users seem to always have it, though.
*Interaction with created files by a user in a different group that has access (via ACL's) is normal--can delete/rename/etc. That same user can also create files in the same directory normally.
*The files that are apparently "read only" to the broken user are created with ownership {nameOfUser}:{nameOfUser'sGroup} and permissions 770.
There you have it and there you are. I'll appreciate any and all attempts to solve this mystery. (Sorry this isn't Treasure Quest, and I'm not Sirius.)
As it is when this happens, I'm creating new groups and adding broken users into them and giving the new group ownership via ACL.
PS A recent development. The most recent share to have a "broken user" on it also has "Segmentation fault" when I try to getfacl the folder. None previous have had this symptom, however.