If I remember correctly, this was a Samba issue where permissions weren't assigned correctly when another Linux system tried to mount the shared drive. What I had to do was set the permissions (and users if need be) in the fstab file itself. So, if I wanted to mount a samba share automatically, my fstab entry might look like this:
//servername/share /mountpoint smbfs uid=500,gid=500,fmask=777,dmask=777,credentials=/home/user/.smbpasswd 0 0
I like using the smbpasswd file as well (or some other name) as that way I don't have to put the username and password in the fstab file.
Using this method, I'm able to mount Samba shares from other Linux partitions with whatever permissions I want.
It would be interesting to see what attributes lsattr would show when mounting a share with the default settings...