I generally use (practice) on Fedora Core, Red Hat 9 & Knoppix 3.7
Sometimes a command { such as [ ]$ cp /etc/passwd . } doesnt work. i.e., Permission deno\ied message appears.
Even sometimes when I make 2 -3 users with same group & same home dir. only 1 out of 3 user is able to login at a time.