How can I get my Macs to see my SAMBA file sharing server?

How can I get my Macs to see my SAMBA file sharing server?

I have recently set up a SAMBA file share. After going through a series of
steps, I have finally been able to have most of my computers see this
server. The primary requirements were: 1) it had to be password protected,
2) have multiple users, 3) each user can own a file, but all users can
write to each others' files.
I am in an office with 5 Macs, 1 Linux Server (Ubuntu 13.04), 1 Windows
Server (Windows 2008 R2), and three Windows XP Pro desktops. All computers
can access the share properly, except the Macs.
Oddly enough, ONE Mac is able to view the share and login. All the other
Macs fail to login after putting in the username and password.
Here are the contents of my smb.conf file:
[global]
workgroup = workgroup
server string = %h server (Samba, Ubuntu)
dns proxy = no
log file = /var/log/samba/log.%m
max log size = 1000
syslog = 0
panic action = /usr/share/samba/panic-action %d
security = user
encrypt passwords = yes
obey pam restrictions = yes
unix password sync = yes
passwd program = /usr/bin/passwd %u
passwd chat = *Enter\snew\s*\spassword:* %n\n
*Retype\snew\s*\spassword:* %n\n *password\supdated\ssuccessfully* .
pam password change = yes
map to guest = bad user
usershare allow guests = yes
username map = /etc/samba/smbusers
guest ok = no
guest account = nobody
comment = Home Directories
browseable = no
read only = no
create mask = 0775
directory mask = 0775
[printers]
comment = All Printers
browseable = no
path = /var/spool/samba
printable = yes
; guest ok = no
; read only = yes
create mask = 0700
[print$]
comment = Printer Drivers
path = /var/lib/samba/printers
[interactive]
path = /home/shok07a/interactive
writeable = yes
browseable = yes
comment = interactive
create mask = 0777
directory mask = 2777
force directory mode = 2777
guest ok = no
force group = sambashare