I was having problems reading all files on an extra hard drive so I attempted to "fix" this with these commands as root:
chown dave:dave /media/250GB chmod 644 * /media/250GB
I'm now unable to see the drive and mount it in my Nautilus shortcuts and I need to go into Nautilus → File System → media → 250GB to see my files. I had two folders in the drive both with backed up data, but both folder now show as files which Nautilus doesn't know what to do with them (it doesn't treat them as folders).
ls -l reports:
...:/media/250GB$ ls -l total 8 drwxr-xr-x 4 root root 4096 2013-01-23 19:24 2013-HOME-BACKUP drwxr-xr-x 11 root root 4096 2013-01-23 19:22 2013-WORK-BACKUP