Thanks Ian. i've tried that with uucp group. No success. Here's the shell response
[guess@localhost ~]$ su -c "gpasswd -a guess uucp"
Password:
Adding user guess to group uucp
[guess@localhost ~]$ minicom
LANG/ja
LANG/ko
LANG/ru
Cannot create lockfile. Sorry.
[guess@localhost ~]$ ls -l /dev/ttyS*
crw-rw---- 1 guess uucp 4, 64 Jan 14 11:59 /dev/ttyS0
crw-rw---- 1 guess uucp 4, 65 Jan 14 11:59 /dev/ttyS1
crw-rw---- 1 guess uucp 4, 66 Jan 14 11:59 /dev/ttyS2
crw-rw---- 1 guess uucp 4, 67 Jan 14 11:59 /dev/ttyS3
I did try again adding guess to group root. User "Guess" can then start minicom. But if this is the case then I will have to restrict "guess" as not to change root password or edit sudoer file as in your other thread
http://mandrivausers.org/index.php?showtopic=33038.